Friday, March 24, 2017

Preparation and evaluation of a novel therapeutic dairy-based drink for weight loss

. 2010 Feb; 2(2): 66–70.
PMCID: PMC3354437

Preparation and evaluation of a novel therapeutic dairy-based drink for phenylketonuria

Ahmed M. Abdel-Salam1,2 and Laila K. Effat3
Author information ► Copyright and License information ►

Introduction

Phenylketonuria (PKU) is one of the most common inborn metabolic errors; if not diagnosed and treated early by special diet intervention it will result in mental retardation. The disorder is associated with deficient activity of the enzyme phenylalanine hydroxylase (PAH), which results in elevated concentrations of phenylalanine (Phe) and its metabolites (phenylketones) in the body fluids of affected individuals. Untreated, affected individuals develop severe to profound mental disabilities, behavioral difficulties, seizures, rashes, pigment dilution, and an unusual body odor[]. The hallmark of PKU is the very high level of phenylalanine due to the variable deficiency of phenylalanine hydroxylase activity. These high levels of phenylalanine can be modified by the restriction of dietary phenylalanine[].
Phenylketonuria is an autosomal recessive inborn error of phenylalanine metabolism resulting from deficiency of phenylalanine hydroxylase. Most forms of PKU and hyperphenylalaninaemia (HPA) are caused by mutations in the PAH gene on chromosome 12q23.2[]. Initiation and control of phenylalanine levels in the early years of life are crucial and important throughout childhood, especially for cognitive function and behavior[].
Milk constituents have become recognized as functional foods, suggesting their use has a direct and measurable effect on health outcomes[]. Whey, a by-product of cheese manufacture, was early considered as a waste product. Recent discoveries have shown whey to be a functional food with several nutritional applications. Milk contains two primary groups of proteins; the caseins and whey proteins. In cheese making, the caseins are responsible for making curds while in an aqueous environment. The components of cheese whey include β-lactoglobulin, α-lactalbumin, bovine serum albumin, lactoferrin, immunoglobulins, lactoperoxidase enzymes, glycomacropeptides, lactose and minerals[].
Glycomacropeptide (GMP) is also referred to as casein macropeptide. GMP is present in whey at about 10-15%, due to the action of chymosin on casein during the cheese-making process. However, it is not produced in acid-coagulated cheeses[]. The κ-casein GMP is an important proteolytic action marker, being useful to ensure the quality control of raw milk as well as to control industrial processes, mainly in the production of cheese and sweet whey. The determination of sialic acid in sweet whey is useful since the concentration of sialic acid reflects the amount of GMP present. Glycomacropeptide is known to be a biologically active compound and is considered to be a potential ingredient for functional foods and pharmaceuticals[–]. One of the main characteristics of GMP composition is the lack of aromatic amino acids including phenylalanine. Therefore, GMP has been evaluated as a potential source of protein in the diet of subjects suffering from PKU.
The present work aimed to prepare and evaluate a novel dairy-based drink based on an emulsion of corn oil with GMP in milk permeate for feeding PKU patients. This dairy-based drink would offer a locally produced and affordable product with a low content of phenylalanine for patients suffering from PKU.

Patients and Methods

Buffalo (Bubalus bubalis) and cow (Bos taurus) milk of healthy lactating animals was obtained from a local farm in the vicinity of Giza, Egypt. Glycomacropeptides (BioPur-GMP™) were purchased from Davisco, USA. Corn germ oil was obtained from the local market in Egypt.

Preparation and properties of the novel dairy-based drink

Fresh mixed whole buffalo and cow milks (1:1) were ultrafiltered though stainless-steel tubing in a pilot plant equipped with an ultrafiltration inorganic membrane (Carbosep®, France). The temperature was maintained at 50-55°C during processing to get milk retentate and permeate. Ultrafiltered (UF) milk permeate (composed of water, sugar, some minerals and non-protein nitrogen compounds) was collected and used as an aqueous solution for the dairy-based drink. The dairy-based drink product was prepared by emulsification of 3% corn germ oil (a fat source) in milk permeate (aqueous solution) containing 2.50% glycomacropeptides (a protein source). The final product was then heated to 85°C for 15 minutes, then cooled rapidly and stored at 4°C.

Human subject nutritional studies

The human subject nutritional studies were conducted according to the Helsinki Declaration and approved by the Ethics Committee of the National Research Centre (NRC), Egypt. The subject studies were carried out under the supervision of approved medical staff in the PKU Unit, Medical Practice Units, Division of Medical Sciences, NRC, Egypt. Patients with PKU following the strict diet of limited phenylalanine content volunteered to test the novel dairy-based drink. The volunteer subjects were male and female and included infants, children, and adults.
Other foods consumed by the volunteer subjects, such as low protein breads and another special milk formula containing a low concentration of phenylalanine (resulting from protein hydrolysis and adsorption of phenylalanine) were monitored for phenylalanine level before the trial.

Serum phenylalanine determination

Measurements of serum phenylalanine levels before and after the trial were carried out using the methods described by Aldis et al[].

Analysis of the novel dairy-based drink for patients with PKU

The total solids, protein, ash, total sugars, and fatty acid content of the novel dairy-based drink were determined according to official methods of the Association of Official Analytical Chemists (AOAC) (11). The pH was measured using a digital pH meter with glass electrodes. Amino acid content of the dairy-based drink was calculated from the amino acid content of the glycomacropeptide obtained from Davisco, USA.
The sensory evaluation of the appearance, color, flavor and overall properties of the novel dairy-based drink were adopted from the National Aeronautics and Space Administration (NASA) (12) using the following scale: (+++) very good, (++) good, (+) acceptable, (-) not acceptable.

Results

A schematic representation of the production of the novel dairy-based drink for PKU patients is shown in Figure 1. The novel dairy-based drink was prepared by emulsifying corn germ oil (a fat source) with casein glycomacropeptide (a protein source) solution in milk permeate.
Fig. 1
A schematic representation of the preparation of the novel dairy-based drink for PKU patients
The chemical composition, nutrient information, and amino acids profile of the novel dairy-based drink are shown in Tables ​Tables11 and ​and2.2. Each 100 mL of the novel dairy-based drink had 53.80 kilocalories. The sensory evaluation properties of the dairy-based drink are shown in Table 3. The results showed that the product was ranked “good” and was acceptable to all volunteers.
Table 1
Chemical composition and calories per 100 mL of the novel dairy-based drink for patients with PKU
Table 2
Amino acid profile of the novel dairy-based drink for patients with PKU
Table 3
Sensory evaluation properties of the novel dairy-based drink for patients with PKU
The phenylalanine levels in patients before and after consumption of the novel dairy-based drink are shown in Table 4. The patients with PKU followed strict diets limiting phenylalanine consumption. The data show that the serum phenylalanine levels were lower after the consumption of the novel dairy-based drink in all patients. The percent reduction in phenylalanine levels ranged from 30 to 80% in all of the groups tested (Table 4).
Table 4
Serum phenylalanine (Phe) levels in patients before and after consumption of the novel dairy-based drink for 3 days
The data were used to calculate suggested daily quantities of the novel dairy-based drink for infancy, childhood and adult ages, as shown in Table 5.
Table 5
The suggested daily quantities of the novel dairy-based drink for patients with PKU at different ages

Discussion

People with phenylalanine levels of 20.0 mg/dL or higher are considered likely to have “classical” PKU. Infants with these high levels are further tested to confirm the diagnosis before treatment is started. Some infants will have more modest elevations of blood phenylalanine and are said to have “mild hyperphenylalanemia.” Many clinicians believe that any child with a phenylalanine level greater than 6 or 8 mg/dL should be treated with a modified phenylalanine restricted diet[].
Providing products high in protein but low in phenylalanine for patients with PKU is the focus of many research groups.
Glycomacropeptide (GMP) is a casein-derived whey peptide. When milk is treated with chymosin during cheese making, the milk protein (k-casein) is hydrolyzed into two peptides. The larger peptide containing amino acid residues 1-105 is called para-k-casein, which becomes part of the cheese curd, while the smaller peptide containing amino acid residues 106-169 becomes soluble and part of the whey. The peptide is relatively small, with a molecular weight of 8000 Daltons. There are two major variants of GMP, variant A and variant B, which differ in two amino acids. Different abbreviations are used to identify GMP, but all refer to the same molecule found in whey. GMP is also produced during curd formation by the act of rennin. Many researchers and health experts believe that GMP appears to have many health benefits beyond nutrition and consider it a functional food. Researchers have indicated that GMP can be used as a medical foodstuff for individuals suffering from PKU. Patients with PKU cannot digest phenylalanine, an essential phenolic amino acid, due to a defect in the enzyme hydroxylase.[–]. GMP is interesting in that it is naturally low in phenylalanine and has the potential to be used as a protein source in PKU diets.
The novel dairy-based drink that was evaluated in this study contained most of the basic amino acids but had a low level of tryptophan (3mg/100 mL). Fortification of the dairy-based drink with basic amino acids such as tryptophan will be taken into consideration in further studies.
Traditionally, strict adherence to the low phenylalanine diet was recommended for the first four to eight years of life, after which it was felt that a liberalization of protein intake could occur without damage to the developed central nervous system[]. Early detection of maternal PKU in pregnant women may also be beneficial. If the mother does not follow a restricted phenylalanine diet during pregnancy, there is an overwhelming risk of the birth of an abnormal child. This risk appears to increase as the average maternal levels of phenylalanine during pregnancy increase[].
In Egypt, people prefer buffalo milk because it is lower in cholesterol and higher in calcium than cow milk. The high milk solids of buffalo milk not only make it ideal for processing into superb dairy products, but also contribute to significant energy savings in conducting that process. Many cheese factories use mixtures of cow and buffalo milk, making this a readily available component for preparing the dairy-based drink for phenylketonuria.

Conclusion

The novel dairy-based drink for phenylketonuria seems a promising therapeutic product for patients. PKU patients are deprived of all animal protein sources rich in phenylalanine content, so an adequate replacement is mandatory. In addition, this novel dairy-based drink has the advantage of the natural taste and smell of milk, and it is affordable. Longer term evaluation of the effects of this novel dairy-based drink on patients with PKU is recommended in order for it to be commercially developed.

Acknowledgement

The authors thank Prof. Dr. M. H. Abd El-Salam, Professor of Dairy Science, National Research Centre and Editors of Journal of Egyptian Dairy Science for his scientific suggestions, advice, and review of this manuscript. The authors thank Dr. Belinda Peace for assistance of English language editing.

References

1. Scriver CR, Eisensmith RC, Woo SL, Kaufman S. The hyperphenylalaninemias of man and mouse. Annu Rev Genet. 1994;28:141–165. [PubMed]
2. Kaufman S. Phenylketonuria: biochemical mechanisms. Adv Neurochem. 1977;2:1–132.
3. Williams RA, Mamotte CD, Burnett JR. Phenylketonuria: an inborn error of phenylalanine metabolism. Clin Biochem Rev. 2008;29(1):31–41. [PMC free article] [PubMed]
4. Azen CG, Koch R, Friedman EG. Intellectual development in 12-year-old children treated for phenylketonuria. Am J Dis Child. 1991;145:35–39. [PubMed]
5. Gill HS, Rutherford KJ, Cross ML. Bovine milk: a unique source of immunomodulatory ingredients for functional foods. In: Buttriss J, Saltmarsh M, editors. Functional Foods II--Claims and Evidence. Cambridge, England: Royal Society of Chemistry Press; 2000. pp. 82–90.
6. Walzem RL, Dillard CJ, German JB. Whey components: millennia of evolution create functionalities for mammalian nutrition: what we know and what we may be overlooking. Crit Rev Food Sci Nutr. 2002;42:353–375. [PubMed]
7. Brody EP. Biological activities of bovine glycomacropeptide. Br J Nutr. 2000;84:39–46. [PubMed]
8. Abd El-Salam MH, El-Shibiny S, Buchheim W. Characteristics and potential uses of the casein macropeptide. Int Dairy J. 1996;6:327–341.
9. Nakano T, Ozimek L. Determination of sialic acid by the thiobarbituric acid reaction in sweet whey and its fractions. J Agric Food Chem. 1999;47:2613–2616. [PubMed]
10. Aldis B, Hoffman G, Therrell BL. Laboratory methods for phenylalanine analysis on newborn screening specimens. In: Therrell BL, editor. Laboratory Methods for Neonatal Screening. Washington, DC: American Public Health Association; 1993. pp. 47–75.
11. Kenneth Helrich. 15th ed. U.S.A.: Association of Official Analytical Chemists Arlington, Virginia, 22201; 1990. A.O.A.C. Official Method of Analysis of Association of Official Analytical chemist.
12. USA: Nutritional Biochemistry Laboratory Johnson Space Center Houston, TX; 1999. N.A.S.A. Space Food and Nutrition an Educator's Guide. http://spacelink.nasa.gov/space.food .
13. Yannicelli S, Ryan A. Improvements in behavior and physical manifestations in previously untreated adults with phenylketonuria using a phenylalanine-restricted diet: a national survey. J Inheri Metabol Dis. 1995;18:131–134. [PubMed]
14. Fiat AM, Chevan J, Jollès P, Waard P De, Vliegenthart FG, Piller F, Caron JP. Structural variability of the neutral carbohydrate moiety of cow colostrum κ-casein as a function of time after parturition.Identification of a tetrasaccharide with blood group1 specificity. Eur J Biochem. 1988;173:253–259. [PubMed]
15. Dziuba J, Minkiewicz P. Influence of glycosylation on micelle-stabilizing ability and biological properties of c-terminal fragments of cow's κ-casein. Int Dairy J. 1996;6:1017–1044.
16. Lopez-Fandino R, Acedo MI, Ramos M. Comparative study by HPLC of caseinomacropeptides from cow's, ewe's and goat's milk. J. Dairy Res. 1993;60:117–121. [PubMed]
17. Lim K, van Calcar SC, Nelson KL, Gleason ST, Ney DM. Acceptable low-phenylalanine foods and beverages can be made with glycomacropeptide from cheese whey for individuals with PKU. Mol Genet Metab. 2007;92:176–178. [PMC free article] [PubMed]
18. Bruck WM, Redgrave M, Tuohy KM, Lonnerdal B, Graverholt G, Hernell O, Gibson GR. Effects of bovine alpha-lactalbumin and casein glycomacropeptide-enriched infant formulae on faecal microbiota in healthy term infants. J Pediatr Gastroenterol Nutr. 2006;43:673–679. [PubMed]
19. McDonald JD, Bode VC, Dove WF, Shedlovsky A. Pahhph-5: a mouse mutant deficient in phenylalanine hydroxylase. Proc Natl Acad Sci USA. 1990;87:1965–1967. [PMC free article] [PubMed]
20. Rogers QR, Harper AE. Amino acid diets and maximal growth in the rat. J Nutr. 1965;87:267–73.[PubMed]
21. Berman PW, Waisman HA, Graham FK. Intelligence in treated phenylketonuric children: A developmental study. Child Develop. 1966;37:731–747.
22. Platt LD, Koch R, Hanley WB, Levy HL, Matalon R, Rouse B, Trefz F, de la Cruz F, Güttler F, Azen C, Friedman EG. The international study of pregnancy outcome in women with maternal phenylketonuria: report of a 12-year study. Am J Obstet Gynecol. 2000;182:326–333. [PubMed]
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OBESITY EPIDEMIC AMONG CHILDREN

the prevalence of obesity among U.S. children aged 2-5 years rose from approximately 5 percent in the early 1970s, the period used to establish a baseline for obesity, to 8.4 percent in 2012 (Ogden et al., 2014). As of 2012, approximately one in seven children in this age group was overweight (Fryar et al., 2012). The average 5-year-old girl in the United States weighed 43.2 pounds in 1976-1980 and 46.6 pounds in 2007-2010 (Fryar et al., 2012; Najjar and Rowland, 1987).


• The flavors of the foods children experience beginning in utero and continuing during breastfeeding and complementary feeding establish flavor and food preferences that can persist throughout a lifetime. (Mennella) • The birth of a child is an event that can motivate parents to change long-established behaviors. (Mennella)
Only 10 out of 50 states of USA have  obesity rates less than  13%

Human beings are 99.9 percent identical at the genetic level, noted Barkin, yet still have many differences (NHGRI, 2014). Part of the reason for these differences is epigenetics. Barkin defined the science of epigenetics as the study of changes in the expression of genes via post-translational and
post-transcriptional modifications. “Think of it this way,” she said. “You can’t change your genes, but you can change the way your genes behave.”
when the larvae of docile European bees are placed in the hives of the killer bee, the normally placid European bees acquire a phenotype identical to that of killer bees (Dobbs, 2013). “The genes didn’t change, but the expression of the genes did,” said Barkin.
Barkin stated that maternal nutrition also affects the microbiome of mothers and their children—the community of single-celled organisms that live in close association with the body (Peterson et al., 2009). In a study of Japanese macaques, for example, mothers on a Western diet high in fats experienced a shift in microbiome species that affected lipid metabolism and inflammatory response (Friedman, 2015). Exposure to a maternal Western diet appears to pattern the microbiome and effect a pro-inflammatory state in infants (Friedman, 2015; Kumar et al., 2014). Although studies in the past have focused on correlations, many studies currently under way are looking at causation, Barkin reported.


Many chronic illnesses that plague society derive in large part from poor food choices that are dictated by people’s taste preferences,

“We don’t have a problem of children over-consuming broccoli,” she said. “They are over-consuming added sugars and salt, [with] too few fruits and vegetables. This pattern of food choice that is evident in the youngest members of our society mirrors that of our nation’s adults.”

Mennella pointed to two factors that can predispose some children to consume obesogenic diets: inborn, evolutionarily driven taste preferences, and the detrimental consequences of not being exposed to the flavors of healthful foods early in life


In an environment with limited nutrients and abundant poisonous plants, sensory systems evolved to detect and prefer the once rare energy (carbohydrate)-rich and sodium-rich foods that taste sweet and salty and to reject toxic foods that taste bitter

The chemical senses that underlie the flavors of foods and beverages are functioning by at least the second trimester of pregnancy
Taste receptors are found not only in the oral cavity but also in the nasal cavity and in the gut), and activation of these receptors in the mouth can be a source of extreme pleasure or pain. While some responses are inborn (e.g., the liking of sweets, they can be shaped by learning.


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Yet another stupidity of EHR EHR

Yet another  stupidity of EHR EHR
 Look at the filters ! What is left  right or BILATERAL ABOUT Diabetes ?

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Low cost Infertility Treatment

Two years after the following article was published where are we ?


Low-cost fertility treatment

Anonymous. The Economist; London412.8896 (Jul 19, 2014): 53.

Abstract

Translate [unavailable for this document]
In France, says Fabrice Houdart, as he dandles his baby, we are like a circus attraction. The Frenchman lives in Washington, DC, with his American boyfriend and their two children, who were conceived using eggs from a Californian donor and born by a surrogate in Pennsylvania. Families built with such a variety of help are still rare enough to raise eyebrows. But across the rich world test-tube babies no longer draw a second glance. For the infertile couples it helps, IVF is close to a miracle. But for many more, the cost is prohibitive.

Full Text

    Translate [unavailable for this document]
In vitro fertilisation, once seen as miraculous, is now mainstream in rich countries. Soon it may be cheap enough to help infertile people in poor places, too
"IN FRANCE," says Fabrice Houdart, as he dandles his baby, "we are like a circus attraction." The Frenchman lives in Washington, DC, with his American boyfriend and their two children, who were conceived using eggs from a Californian donor and born by a surrogate in Pennsylvania. Families built with such a variety of help are still rare enough to raise eyebrows. But across the rich world "test-tube babies" no longer draw a second glance. Since the first, Louise Brown, was born in 1978, 5.5m more have followed, half of them in the past six years.
Back then, doctors had to hope that the single egg they retrieved would be fertilised when mixed with sperm, and that the resulting embryo would be a winner. Success rates were just a few percent. Now, with stronger drugs to stimulate ovulation and better laboratory techniques to manipulate and store embryos, more than a quarter of IVF attempts result in a baby.
For the infertile couples it helps, IVF is close to a miracle. But for many more, the cost is prohibitive. Public health programmes in some rich countries, including Australia, Japan and several European ones, cover IVF for some who need it, but rarely all. Britain's National Health Service, for example, does not manage to pay for the three tries its guidelines recommend for all who would benefit. In America, where IVF is rarely covered by insurance and an attempt costs around $15,000, at most a quarter of those for whom IVF is clinically indicated are actually treated.
The unmet need in developing countries is higher still. That is partly because people have less money, but also because infertility is more common. Genital mutilation, unsafe abortion and poorly attended births cause infections that leave women with blocked Fallopian tubes, making normal conception impossible. Sexually transmitted diseases scar both men's and women's reproductive systems. The World Health Organisation estimates that around 50m couples worldwide have been trying to conceive for at least five years without success. Almost none of those in developing countries can hope to get treatment.
The grief of infertility is sharper in poor countries, too. In Africa and much of Asia it carries a stigma, nearly all borne by women. Male-factor infertility is rarely acknowledged except when a man has failed to father children with several women. A "barren" wife is often ostracised, beaten or abandoned, or infected with HIV/AIDS as a result of her husband straying in the hope of a child. She is at higher risk of being murdered or committing suicide.
Better health care would mean fewer people in developing countries becoming infertile in the first place. Now fertility doctors are trying to make IVF cheap enough to help many more of those who will still need it. Some are simplifying diagnosis, skipping some tests that are currently standard, but still doing enough to tell, for most patients, which treatment would be best.
Others are cutting spending on equipment. Last year Belgian researchers tested a shoebox-sized IVF laboratory built from cheap glass tubes that uses baking soda and citric acid to create the carbon dioxide needed for fertilisation to occur. Pregnancy rates matched those from a standard laboratory and set-up costs are 85-90% lower. With fewer tests and less monitoring, running costs are slashed, too. Though of no use when the man's sperm is sub-par and thus needs to be injected into the egg under a pricey microscope, it should be sufficient for about 70% of infertile couples, says Willem Ombelet of the Genk Institute for Fertility Technology, who led the first trial.
The Low-Cost IVF Foundation, a non-profit based in Switzerland, is working with Zambia's health ministry to set up an IVF programme later this year. Costs will be shaved wherever possible, with the biggest saving coming from using clomiphene citrate, an oral drug that provides a modest boost to ovulation and costs just $12 per IVF attempt, instead of the standard injectable drugs, which cost thousands.
Cut-price approaches will not be suitable for all couples, and success rates per IVF cycle may be lower. But if the savings are big enough, more infertile couples will be able to try at least once and the cost per baby will plummet. The Foundation's long-term aim is to show IVF can be included in a developing country's public health-care system for as little as $300 per attempt, plus staffing costs. Gauging how achievable that figure is will only be possible once such treatment is up and running, says Ian Cooke, an emeritus professor at Sheffield University in England and one of its founders. If the programme in Zambia gets anywhere close to it, clinics in rich countries could start slashing prices, too.

Anonymous. The Economist; London412.8896 (Jul 19, 2014): 53.

from  Anonymous. The Economist; London412.8896 (Jul 19, 2014): 53.
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Wednesday, March 22, 2017

 Classification of overweight &obesity in adults as per BMI

Classification BMI (kg/m2)

 Underweight >18.5
Normal range 18.5—24.9
Overweight >25
Pre-obese 25.0—29.9
Obese class I 30.0—34.9
Obese class II 35—39.9
Obese class III >40

Source: WHO

 Sex-specific waist circumference measurements for
identification of individuals at increased health risk due to
intra-abdominal fat accumulation
Waist circumference
(cm)
Risk of metabolic complications
                                                                  Men       Women
Alerting zone Increased                             94           80
Action zone Substantially increased         102           88

Adapted from WHO 
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WHAT IS OBESITY AND HOW IS IT MEASURED?

Measuring Obesity



\




From Calipers to CAT Scans, Ten Ways to Tell Whether a Body Is Fat or Lean

What’s the best way to determine whether a body is fat or fit? Body fat can be measured in several ways, with each body fat assessment method having pros and cons.
  • The most basic method, and the most common, is the body mass index (BMI). Doctors can easily calculate BMI from the heights and weights they gather at each checkup; BMI tables and online calculators also make it easy for individuals to determine their own BMIs.
  • The BMI and other so-called “field methods”-among them, waist circumference, waist-to-hip ratio, skinfold thicknesses, and bioelectrical impedance-are useful in clinics and community settings, as well as in large research studies.
  • More sophisticated methods, such as magnetic resonance imaging or dual energy X-ray absorptiometry, are so-called “reference measurements”-techniques that are typically only used in research studies to confirm the accuracy of (or as scientists say, to “validate”) body measurement techniques.
  • Several methods can’t be used in children or pregnant women, due to safety concerns, or are less accurate in people who are very overweight. (1)
Here is a brief overview of some of the most popular methods for measuring body fat-from basic body measurements to high-tech body scans-along with their strengths and limitations. (Adapted from (1))

Body Mass Index (BMI)

Body mass index (BMI) is the ratio of weight to height, calculated as weight (kg)/height (m2), or weight (lb)/height (in2) multiplied by 703.
Strengths
  • Easy to measure
  • Inexpensive
  • Standardized cutoff points for overweight and obesity: Normal weight is a BMI between 18.5 and 24.9; overweight is a BMI between 25.0 and 29.9; obesity is a BMI of 30.0 or higher
  • Strongly correlated with body fat levels, as measured by the most accurate methods
  • Hundreds of studies show that a high BMI predicts higher risk of chronic disease and early death.
Limitations
  • Indirect and imperfect measurement-does not distinguish between body fat and lean body mass
  • Not as accurate a predictor of body fat in the elderly as it is in younger and middle-aged adults
  • At the same BMI, women have, on average, more body fat than men, and Asians have more body fat than whites

Waist Circumference

Waist circumference is the simplest and most common way to measure “abdominal obesity”-the extra fat found around the middle that is an important factor in health, even independent of BMI. It’s the circumference of the abdomen, measured at the natural waist (in between the lowest rib and the top of the hip bone), the umbilicus (belly button), or at the narrowest point of the midsection.
Strengths
  • Easy to measure
  • Inexpensive
  • Strongly correlated with body fat in adults as measured by the most accurate methods
  • Studies show waist circumference predicts development of disease and death
Limitations
  • Measurement procedure has not been standardized
  • Lack of good comparison standards (reference data) for waist circumference in children
  • May be difficult to measure and less accurate in individuals with a BMI of 35 or higher

Waist-to-Hip Ratio

Like the waist circumference, the waist-to-hip ratio (WHR) is also used to measure abdominal obesity. It’s calculated by measuring the waist and the hip (at the widest diameter of the buttocks), and then dividing the waist measurement by the hip measurement.
Strengths
  • Good correlation with body fat as measured by the most accurate methods
  • Inexpensive
  • Studies show waist-to-hip ratio predicts development of disease and death in adults
Limitations
  • More prone to measurement error because it requires two measurements
  • More difficult to measure hip than it is to measure waist
  • More complex to interpret than waist circumference, since increased waist-to-hip ratio can be caused by increased abdominal fat or decrease in lean muscle mass around the hips
  • Turning the measurements into a ratio leads to a loss of information: Two people with very different BMIs could have the same WHR
  • May be difficult to measure and less accurate in individuals with a BMI of 35 or higher

Skinfold Thickness

In this method, researchers use a special caliper to measure the thickness of a “pinch” of skin and the fat beneath it in specific areas of the body (the trunk, the thighs, front and back of the upper arm, and under the shoulder blade). Equations are used to predict body fat percentage based on these measurements.
Strengths
  • Convenient
  • Safe
  • Inexpensive
  • Portable
  • Fast and easy (except in individuals with a BMI of 35 or higher)
Limitations
  • Not as accurate or reproducible as other methods
  • Very hard to measure in individuals with a BMI of 35 or higher

Bioelectric Impedance (BIA)

BIA equipment sends a small, imperceptible, safe electric current through the body, measuring the resistance. The current faces more resistance passing through body fat than it does passing through lean body mass and water. Equations are used to estimate body fat percentage and fat-free mass. (1)
Strengths
  • Convenient
  • Safe
  • Relatively inexpensive
  • Portable
  • Fast and easy
Limitations
  • Hard to calibrate
  • The ratio of body water to fat may be change during illness, dehydration or weight loss, decreasing accuracy
  • Not as accurate as other methods, especially in individuals with a BMI of 35 or higher

Underwater Weighing (Densitometry)

Individuals are weighed in air and while submerged in a tank. (1) Researchers use formulas to estimate body volume, body density, and body fat percentage. Fat is more buoyant (less dense) than water, so someone with high body fat will have a lower body density than someone with low body fat. This method is typically only used in a research setting.
Strengths
  • Accurate
Limitations
  • Time consuming
  • Requires individuals to be submerged in water
  • Generally not a good option for children, older adults, and individuals with a BMI of 40 or higher

Air-Displacement Plethysmography

This method uses a similar principle to underwater weighing but can be done in the air instead of in water. (1) Individuals sit in a small chamber wearing a bathing suit; one commercial example is the “Bod Pod.” The machine estimates body volume based on air pressure differences between the empty chamber and the occupied chamber.
Strengths
  • Relatively quick and comfortable
  • Accurate
  • Safe
  • Good choice for children, older adults, pregnant women, individuals with a BMI of 40 or higher, and other individuals who would not want to be submerged in water
Limitations
  • Expensive

Dilution Method (Hydrometry)

Individuals drink isotope-labeled water and give body fluid samples. Researchers analyze these samples for isotope levels, which are then used to calculate total body water, fat-free body mass, and in turn, body fat mass. (1)
Strengths
  • Relatively low cost
  • Accurate
  • Safe
  • Can be used in individuals with a BMI of 40 or higher, as well as in children and pregnant women
Limitations
  • The ratio of body water to fat-free mass may change during illness, dehydration, or weight loss, decreasing accuracy

Dual Energy X-ray Absorptiometry (DEXA)

X-ray beams pass through different body tissues at different rates. So DEXA uses two low-level X-ray beams to develop estimates of fat-free mass, fat mass, and bone mineral density. (1) DEXA is typically only used for this purpose in research settings.
Strengths
  • Accurate
Limitations
  • Equipment is expensive and cannot be moved
  • Cannot accurately distinguish between different types of fat (fat under the skin, also known as “subcutaneous” fat vs. fat around the internal organs, or “visceral” fat)
  • Cannot be used with pregnant women, since it requires exposure to a small dose of radiation
  • Most current systems cannot accommodate individuals with a BMI of 35 or higher

Computerized Tomography (CT) and Magnetic Resonance Imaging (MRI)

These two imaging techniques are now considered to be the most accurate methods for measuring tissue, organ, and whole-body fat mass as well as lean muscle mass and bone mass. (1) CT and MRI scans are typically only used for this purpose in research settings.
Strengths
  • Accurate
  • Allows for measurement of specific body fat compartments, such as abdominal fat and subcutaneous fat
Limitations
  • Equipment is extremely expensive and cannot be moved
  • CT scans cannot be used with pregnant women or children, due to the high amounts of ionizing radiation used
  • Some MRI and CT scanners may not be able to accommodate individuals with a BMI of 35 or higher

References

1. Hu F. Measurements of Adiposity and Body Composition. In: Hu F, ed. Obesity Epidemiology. New York City: Oxford University Press, 2008; 53–83.

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The aim of the Harvard School of Public Health Obesity Prevention Source Web site is to provide timely information about obesity’s global causes, consequences, prevention, and control, for the public, health and public health practitioners, business and community leaders, and policymakers. The contents of this Web site are not intended to offer personal medical advice. You should seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this Web site. The Web site’s obesity prevention policy recommendations are based primarily on a review of U.S. expert guidance, unless otherwise indicated; in other countries, different policy approaches may be needed to achieve improvements in food and physical activity environments, so that healthy choices are easy choices, for all.
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