Fat tissue protective of immune system and against cancer in pigs
Based on studies of pigs, researchers stated that fat helps fend off illness. Besides keeping a body warmer, fat cells, or adipocytes, produce hormonelike proteins in reaction to invading toxins, behaving much like immune cells that fight disease. "Adipocytes can be functional and beneficial without creating obesity," said Michael Spurlock, an animal sciences professor at Purdue University in West Lafayette, Ind. Writing in the American Journal of Physiology, Spurlock and colleagues from the university's veterinary school said fat cells play a role in helping insulin regulate blood sugar levels and can aid the immune system's response to cancerous cells.(American Journal of Physiology, Jan 2004)
Native American heart disease not linked to
More than 75 percent of middle-aged and older American Indians are overweight or obese (body mass index [BMI] of 25 or over) in recent research on risk factors for heart disease in the Strong Hearty Study of Arizona, Oklahoma, and South/North Dakota. BMI is higher in women than men, in younger than older people, and in those with diabetes versus nondiabetic persons. The majority have central obesity, and percent body fat is extremely high. Yet, paradoxically, increasing obesity had only a modest influence on risk factors for coronary heart disease, and waist circumference had no special effect over BMI on these risk factors. Except for insulin, the changes in risk factors with increasing obesity were not large. Thus, the relations among obesity, body fat distribution, and heart disease risk may differ for American indians. The authors cite a large population study of Pima Indians that shows little relation between obesity and death rates.
The study included 4,549 men and women age 45 to 74 in the three areas. For both men and women, all measures of weight, waist, BMI, and percent body fat were lower in the Dakotas and higher in Arizona, where lifestyles may be more sedentary. (Gray R, Fabsitz R, Cowan L, et al. Relation of generalized and central obesity to cardiovascular risk factors and CHD in American Indians: the Strong Heart Study. Int J Obes 2000;24:849-860)
In Sweden, half the men with low BMIs were not lean
In Swedish studies of 735 men born in 1913 and followed up for 22 years after age 60, many participants who were lean and muscular had a high enough BMI to be misclassified as overweight or obese, because BMI is used as a proxy for body fat. Similarly, less than half of the Swedish men with low BMIs were actually lean. Researchers warned that BMI cannot give an accurate indication of body fat, and even less so for older persons. (Healthy Weight Journal 2000:14:5;67 / Heitmann BL, Erikson H, Ellsinger BM, et al. Mortality associated with body fat, fat-free mass and body mass index among 60-year-old Swedish men. Int J Obes 2000;24:33-37)
Elderly women's mortality risk
rises with weight loss
Older women who are underweight or who lose weight may be at greater risk of dying than women who maintain an average weight or gain a few pounds. In a University of Maryland study, 648 women, age 65 to 99, were interviewed and weighed once a year for 3 years, then followed for an additional 3 years. Women with a low body mass index (BMI) were most likely to die. Of these, 22 percent of women died, compared with 18 percent of women with a high BMI and 13 percent of women with an average weight. Losing weight, regardless of initial BMI, also increased the risk of dying. For example, in women with an average weight, those who lost weight were almost four times as likely to die as women who either maintained that weight or gained a few pounds. The researchers caution that extra medical attention should be paid to older women who lose weight. (Healthy Weight Journal 2000:14:2;18 / McKinney M. Weight loss hikes elderly women's risk of dying. Reuters Health, NY, 12/3/99; J Am Geriatrics Soc 1999; 47:1409-1414.)
Weight loss brings risk, unlike fat loss
Most large studies show an increased risk of death with weight loss. Yet fat loss seems beneficial.
Perhaps the harm of losing lean body mass during weight loss overrides any benefits that might come from fat loss. Testing this theory, researchers at the Obesity Research Center in New York analyzed two large longitudinal cohort studies, the Framingham Heart Study, and the Tecumseh Community Health Study.
Results were remarkably similar in both samples. Weight loss was associated with higher death rates, but fat loss with lower death rates. In the Framingham sample, weight loss of 1 standard deviation or 6.7 kg resulted in a 39 percent increase in mortality risk, and fat loss of 1 standard deviation or 4.8 mm resulted in a 17 percent decrease in risk. In the Tecumseh sample weight loss of 1 sd (4.6 kg) resulted in a 29 percent increase in mortality risk, and fat loss of 1 sd (10 mm) resulted in a 15 percent decrease in risk. Controlling for smoking, baseline values of weight and fat, and using different analyses, basically reached the same outcome and confirmed these results. Whether male or female made little difference, nor did age. Essentially weight loss was revealing a loss of lean body mass, said the researchers.
They suggested this may also imply the opposite: that weight gain is associated with lower death rates and fat gain with higher death rates, but this needs further study.
Implications of the study are clear and profound. Whether weight loss is healthy or not may depend on the amount of fat that is lost and lean that is preserved. The optimal percentage is not clear. It may make a difference how much body fat the person has. It is important to begin measuring fat loss in weight loss programs, they said. (Healthy Weight Journal 1999:13:5;66 / Allison DB, Zannolli R, Faith MS, et al. Weight loss increases and fat loss decreases all-cause mortality rate: results from two independent cohort studies. I J Obesity 1999;23:603-611.)
Death rate lowest at BMI of 34
Disputing guidelines that say health risks begin at a body mass index of 25, the Panel Study of Income Dynamics, which looked at women age 50 and over, found the point of lowest risk to be much higher than this. The four-year study of 1,355 women found a broad U-shaped relationship between BMI and mortality, suggesting that a broad range of weight is well tolerated by older women. Mortality risk was lowest among both smoking and nonsmoking women at a BMI of around 34. High risk at lower weights did not appear to be explained by smoking, as the effect remained when controlled for smoking. (Healthy Weight Journal 1999:13:5;66 / Fontaine KR, Heo M, Cheskin LJ, Allison DB. Body mass index, smoking, and mortality among older American women. J Women's Health 1998;7:1257-1261.)
Deaths shock college wrestling
Three college wrestlers died during workouts in the 6 weeks between November 9 and mid-December 1997, as they tried to lose weight to meet the requirements of their weight classes. Jeff Reese, 21, of the University of Michigan, was wearing a rubber suit and riding a stationary bike trying to lose 6 lbs over a 3-hour period to compete in the 153-lb weight class the next day when he had difficulty breathing, became incommunicative, his legs became unsteady, and he collapsed with cardio-respiratory arrest. Resuscitation was unsuccessful. His preseason weight was 180 lbs. Joseph LaRosa, 22, of the University of Wisconsin-La Crosse also was riding an exercise bike in a rubber suit trying to shed the last 4 pounds to compete in the 153-lb weight class when he died (preseason weight, 178). Billy Saylor, 19, or North Carolina's Campbell University died while attempting to lose 15 lbs over a 12-hour period, to compete in the 195-lb weight class (preseason weight, 33). They were under the supervision of athletic staff when they died.
All three engaged in a similar rapid weight-loss regimen that restricted food and fluid intake and promoted dehydration through perspiration, according to a Centers of Disease Control report. They attempted to maximize sweat losses by wearing vapor-impermeable suits under cotton warm-up suits and exercising vigorously in hot environments, which resulted in hyperthermia.
These were the first identified deaths associated with weight loss in interscholastic or collegiate wrestling since national record keeping began in the United States in 1982. As a result of the deaths, the National Collegiate Athletic Association revised the guidelines governing weight-loss practices and weigh-in procedures and added penalties for noncompliance. They now prohibit use of laxatives, emetics, diuretics, excessive food and fluid restriction, self-induced vomiting, hot rooms greater than 79 degrees F (26 degrees C), hot boxes, saunas, steam rooms, vapor-impermeable suits, and artificial rehydration techniques such as intravenous hydration before competition. In addition, NCAA temporarily added a 7-lb weight allowance to each weight class, required all wrestlers to compete only in the weight class they were in on January 7, and stipulated that all weigh-ins be held no more than 2 hours before the beginning of competition. (Healthy Weight Journal 1998:12:3;34 / Hyperthermia and dehydration-related deaths in three collegiate wrestlers. Centers of Disease Control and Prevention, MMWR February 20, 1998; 47;105-108); Wrestling training deaths, AP December 20, 1997)
Risks of early death for obesity way less than expected
Premature mortality associated with obesity was less than expected in a German study at Heinrich-Heine University in Dusseldorf.
For 6,053 obese patients followed for an average of 14 years there was no significantly increased mortality up to a body mass index of 32, and only moderate risk up to 36. Even in the heaviest group with a BMI of 40 or more, the risk was only double for women; it was triple for men in this group.
Relative risks were: BMI 25 up to 32, women 1.00, men 1.26; BMI 32 to 36, women 1.20, men 1.26; BMI 36 to 40, women 1.27, men 1.92; BMI 40 and over, women 2.31, men 3.05. Mortality ratios were compared with reference populations in the same locations. (Healthy Weight Journal 1998:12:1;2 / Spraul M, et al. Mortality in Obesity. I J Obesity 1997;21:S2:49:S24)
Low weight predicts fractures for older women
Thin elderly women suffer more fractures than larger women, according to Minnesota researchers working with the Study of Osteoporotic Fractures. In a 6.4-year follow-up of 8,059 women age 65 and older, women in the lowest quartile of weight had 2 to 2.4 times the risk of hip, pelvic, and rib fractures as women in the highest quartile. They conclude that in recommendations for screening and treatment decisions, low weight should be considered a risk factor for these fractures. Weight did not predict fractures of the humerus, elbow, wrist, ankle, or foot. (Healthy Weight Journal 2000:14:6;82 / Low body weight increases risk of some fractures in elderly women. Reuters Medical News, Westport 7/18/00. Ann Inten Med 2000;133:123-127)
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