Waist Hip Ratio

reposted from: http://en.wikipedia.org/wiki/Waist-hip_ratio

The waist-hip ratio in women is often considered a key feature in physical attractiveness.
Measured directly from this image, the frontal WHR of the model in this image is approximately 0.68.

Thighs and abs have a different take on fat

reposted from New Scientist


17:58 05 October 2010 by Debora MacKenzie Magazine issue 2781.

As many women will no doubt attest, not all fat accrues equally. That may be because cells in your thighs and abdomen store fat in different ways.

Michael Jensen and colleagues at the Mayo Clinic in Rochester, Minnesota, put volunteers on a fattening diet for eight weeks and then measured what happened to their fat cells, or adipocytes. While abdominal cells got larger, thigh cells multiplied, by recruiting more adipocytes from pre-fat cells. The more new thigh fat cells recruited, the less abdominal fat people gained.

Fat on the abdomen increases the risk of diabetes and other disorders, while fat on hips and thighs has a protective effect. Jensen thinks thigh fat may soak up excess food energy to keep it away from the abdomen, where fat does more damage.

An individual's tendency to be pear or apple-shaped may in part be set by the ability of their thigh fat cells to recruit more adipocytes. Learning what controls this process may help fight fat's detrimental effects on our health.

Journal reference: Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1005259107


Curvaceous claims go pear-shaped
reposted from: NHS Choices

NHS Choices Tue Oct 05 2010 17:35:00 GMT+0100 (GMT Daylight Time) Share

“Curvy women will live longer,” the Daily Express today reported, saying that Jennifer Lopez, Nigella Lawson and Beyonce “are in great shape to live longer” because of their “well-rounded figures”. According to the news, a study has found that a big bottom and thighs could help to prevent metabolic disorders such as heart disease, stroke and diabetes.

The reports of this study and the newspapers' interpretations are misleading, as they suggest that the study measured health outcomes of people with different body shapes. This was not the case. The study actually assessed the different ways that fat cells in the thighs and abdomen respond to over-eating. In effect, it has illustrated the known phenomenon of people putting on weight in different places in different ways.

The findings of this interesting study – that people who gained more of the weight on their thighs were less likely to have large abdominal fat cells – does not mean that women with bigger hips and a ‘pear-shape’ will live longer.

Where did the story come from?

The study was carried out by researchers from The Mayo Clinic, the Howard Hughes Medical Institute and Yale University. It was funded by a number of US institutions, including the National Institutes of Health, the US Public Health Service, the Noaber Foundation, the Mayo Foundation, and the National Institutes of Health. The study was published in the peer-reviewed medical journal Proceedings of the National Academy of Sciences (PNAS).

The news reports of this study suggest that the research compared the health of participants with different distributions of body fat. It did not. Previous studies have found that fat distribution is important and that the waist-to-hip ratio may be a better predictor of cardiovascular disease risk than BMI values: a higher ratio (more upper body fat than lower body fat) is associated with poorer health. This study actually investigated how the fat cells at these two sites respond to over-feeding.

What kind of research was this?

Studies have shown that the distribution of body fat is an important predictor of the consequences of obesity. Upper-body fat gain is associated with negative consequences, and lower-body fat gain seems to have a protective effect. The researchers say that little is known about the mechanisms that regulate the way fat accumulates.

Other studies have also suggested that from the age of 20, fat gain is likely to be the result of individual fat cells growing in size rather than increases in the numbers of fat cells. However, these findings were based only on investigations of abdominal fat cells.

In this observational study, researchers gave closer investigation to the changes in fat cells at different sites on the body seen in a group of over-feeding adults. Specifically, they were interested in whether there was a difference in the way that the upper body and lower body deposited fat.

What did the research involve?

The researchers recruited 28 healthy adults (15 male, 13 female) with an average age of 29. None of the group were obese (BMI <26kg/m2) or had a history of obesity. None of them were taking medications (except oral contraceptives).

For 10 days, three specially prepared daily meals were provided to maintain current weight. During this time, body composition was assessed using imaging (X-rays, CT scans etc). Samples of fat tissue were obtained from two regions of the body: the abdomen and the thigh.

The participants then began the over-feeding for an eight-week period during which they were instructed to eat until they were more full than usual. They were also provided with supplemental food (ice-cream shakes, chocolate bars or high-calorie drinks). Weight gain was measured regularly. After the eight-week period, participants were admitted back to the unit to have further fat biopsies and other measurements taken. They then returned to a diet that stabilised their weight.

A comparison was made of the size and number of fat cells at the upper and lower-body sites before and after over-feeding. The researchers also measured the activity of the fat cells and responses in the precursor cells that develop into fat cells.

What were the basic results?

As expected, the body weight of the group increased by an average of 4.6kg, due to an increase in fat tissue. These weight gains led to a BMI increase of 1.5kg/m2.

In general, the size of abdominal fat cells increased in response to weight gain, but their number did not. In women, those who had smaller abdominal fat cells to start with saw a greater increase in the size of the cells than those who had normal-sized cells to start with. This pattern was not seen in men.

For the thigh cells, weight gain was more linked to an increase in the number of fat cells rather than an increase in their size. The relative fat gain in the lower body was a ‘negative predictor’ of the change in the size of abdominal fat cells, i.e. people who gained more fat in the lower body were less likely to have large fat cells around their abdomen.

After further modelling, the researchers note that a gain of 1.6kg results in the creation of about 2.6 billion new fat cells within eight weeks. This response of fat cells depended on gender and the size of fat cells seen at the start of the study. For abdominal fat, weight gain seems to be due to an increase in the size of fat cells rather than in cell numbers.

How did the researchers interpret the results?

The researchers say that their results challenge the thinking that the total number of body fat cells remains constant in adults. They say that the ability of healthy adults to expand lower-body fat via hyperplasia (i.e. increasing cell numbers) may prevent or delay abdominal weight gain.

Conclusion

The newspapers have extrapolated the findings from this research to reach unsupported conclusions that “curves will make you live longer”. However, the two key findings of the research are:

• Different mechanisms lie behind weight gain in the abdomen and in the thighs.
• Adults who put on weight in their lower body are less likely to do so in their abdomen.

This illustrates, in an experimental situation, what is already known, i.e. that people gain weight in different places. Despite what newspaper interpretations may suggest, the study did not compare the health of those who gained weight in their thighs with those who gained more weight in their abdomen.

To note:

• The study did not measure health outcomes
• Weight gained (increased size of fat cells) on the abdomen appeared to occur by a different mechanism to that on the thighs
• The greater the change in fat cells in the thigh, the smaller the fat cells in the abdomen. The researchers imply that this may help to explain why some people put on weight on their thighs more readily than around their abdomen.

This is interesting research that illustrates the underlying mechanisms of fat gain in two important regions of the body. It shows that the fat cells of the abdomen behave differently to those of the thigh in individuals who are over-eating. It also shows that people who gain weight in their lower body have smaller fat cells in their abdomen. Crucially, this study does not directly inform the debate about which body shape is healthier.

Links To The Headlines

Pear-shaped secret to long life: Big bottom and thighs lowers risk of disease. Daily Mail, October 5 2010

Curvy women will live longer. Daily Express, October 5 2010

Links To Science

Tchoukalovaa YD, Votrubaa SB, Tchkonia T et al. Regional differences in cellular mechanisms of adipose tissue gain with overfeeding. PNAS [Published online before print] October 4, 2010

Which BMI gives the lowest risk of death? Why the pot belly is a killer.

source: New Scientist, 12 November 2008

An expanding waistline could double your risk of death
(Image: Wikimedia commons)

Updated: 8/8/10.
Crabsallover Notes: Among male participants who had never smoked, the risk of death was lowest:

1. at a BMI of 24.5 (supplementary Figure 2)
2. 85cm waist circumference (supplementary Figure 3)
3. 0.88 waist to hip ratio.(supplimentary Figure 3).

22:00 12 November 2008 by David Robson

Having trouble slipping into those jeans? That expanding belly could as much as double your risk of premature death, even if your weight is considered healthy.

While obesity is a well-known predictor of diabetes, heart disease and some kinds of cancer, a major new study shows that a paunch poses its own particular risks, independently of fat stored elsewhere in the body. This suggests that the size of someone's waistline as well as their body mass index should be taken into account in assessing their health.

The team behind the study, including researchers from Imperial College London and the German Institute of Human Nutrition in Potsdam-Rehbrücke, followed the health of 359,387 people from nine European countries over roughly 10 years. They wanted to examine a link between waistline and health that had been found in earlier smaller-scale studies. Previous animal studies had also suggested that visceral fat around the belly has more negative effects on health than fat in the thighs of the hind legs.

After controlling for factors such as overall obesity, the team found that the risk of premature death among subjects with a waist exceeding 120cm (47.2in) for men and 100cm (39.4in) for women was twice that for those whose waists were under 80cm (31.5in) for men and 65cm (25.6in) for women.

For a given BMI, a 5cm increase in waistline increased the risk of premature death by 17% in men and 13% in women.

A simple predictor of risk

"There aren't many simple individual characteristics that can increase a person's risk of premature death to this extent, independently from smoking and drinking," says Elio Riboli from Imperial College London, who was part of the team.

The ratio of waist size to hip measurement also appears to be an important predictor of the risk of premature death. Most waist-to-hip ratios for men ranged from 0.78 and 1.10 for men, and for a given ratio, an increase by 0.1 increased the chance of premature death by a whopping 34%. Most female waist-to-hip ratios were in the 0.66-0.98 range, and (again for a given ratio) an increase of 0.1 resulted in a 24% jump in risk.

The team speculate that fatty deposits around the waist could secrete elevated levels of hormones and other signalling proteins called cytokines that lead to chronic illnesses like heart disease and cancer.

"Abdominal fat is not a mere energy depot, but it also releases messenger substances that can contribute to the development of chronic diseases. This may be the reason for the link,"

says Tobias Pischon of the German Institute of Human Nutrition.

Review by Crabsallover

Journal reference: New England Journal of Medicine, vol 359, p 2105 (Full Text)
Table 1. Relative Risk of Death According to BMI among Men and Women in the European Prospective Investigation into Cancer and Nutrition.
Current guidelines with respect to obesity recommend the measurement of waist circumference in persons with a BMI between 25.0 and 34.9 and propose cutoff points for waist circumference of 102 cm in men and 88 cm in women (and cutoff points for waist-to-hip ratio of 1.0 in men and 0.85 in women) to define abdominal obesity and to identify persons at risk for disease.² However, less is known about the association of waist circumference or waist-to-hip ratio with the risk of death.

There was a significant nonlinear association of BMI with the risk of death, with the lowest risks at a BMI of 25.3 among men and 24.3 among women

and increased risks in the lower and upper BMI categories (Table 1 and Figure 1).
Figure 1. Adjusted Relative Risk of Death among Men and Women in the European Prospective Investigation into Cancer and Nutrition, According to BMI, Waist Circumference, and Waist-to-Hip Ratio.
The relative risk of death in association with body-mass index (BMI, the weight in kilograms divided by the square of the height in meters), waist circumference, and waist-to-hip ratio is shown in Panel A for men and in Panel B for women. Solid lines indicate relative risks, and dashed lines indicate 95% confidence intervals. The relative risks are plotted on a logarithmic scale.







Table 2. Relative Risk of Death According to Quintiles of Waist Circumference among Men and Women.
According to the Crude measure

the optimum waist measurement is 86-<91.5cm>

After further adjustment for BMI, waist circumference and waist-to-hip ratio showed a strong positive association with the risk of death (Table 2 and Figure 2, and Table 3 in the Supplementary Appendix). For a given BMI in men and women, a waist circumference that was 5 cm larger was associated with a risk of death that was increased by a factor of 1.17 among men and by a factor of 1.13 among women, and a waist-to-hip ratio that was 0.1 unit higher was associated with a risk that was increased by a factor of 1.34 among men and by a factor of 1.24 among women. In models that included waist circumference or waist-to-hip ratio, BMI remained significantly associated with the risk of death. Hip circumference was not significantly associated with the risk of death after adjustment for BMI.

Figure 2. Adjusted Relative Risk of Death among Men and Women, According to Waist Circumference and Waist-to-Hip Ratio after Adjustment for BMI.
The relative risk of death in association with waist circumference and waist-to-hip ratio, after adjustment for BMI, is shown in Panel A for men and in Panel B for women. Solid lines indicate relative risks, and dashed lines indicate 95% confidence intervals. The relative risks are plotted on a logarithmic scale.
Subgroup Analyses

Among participants who had never smoked, the risk of death was lowest at a BMI of 24.5 for men and 23.9 for women

Amongst Men who have never smoked (Supplimentary Figure 3) the lowest risk of death was with 85cm waist circumference / 0.88 waist to hip ratio.

(Figure 2 and Figure 3 in the Supplementary Appendix).

WHO - Preventing the global obesity epidemic - 2000

Total report size: 253 pages
Summary 16 pages - click on Parts 1..2 etc, for additional pdf

Part 1: The problem of Overweight and Obesity

Part 2: Establishing the true costs of the problem of overweight and obesity