Can a Virus Make you Fat? by Jerry Brainum 3/24

 

New diets are constantly being introduced, and many make the best-seller list. The popularity of various diets that offer the promise of promoting safe and long-lasting body fat loss is mute testimony to the prevalence of obesity. Some researchers think that what they call the "obesity epidemic" began in the 1980s, although the precise reason for choosing those years is never apparent. But when asked about the causes of fat gains, several answers emerge, with the most predominant being a lack of balance between calories consumed and physical activity. In short, the prevailing notion of why people get fat is simply that they overeat and don't burn enough calories through physical activity. According to this idea, losing excess body fat involves eating fewer calories and increasing physical activity, especially consuming fewer calories than you burn through physical activity. While that equation has scientific merit, it doesn't seem efficient. Studies show that 95% of those who lose weight by dieting regain it all within a year or so. 

Others suggest that just blaming the consumption of excess calories to explain body fat gains is too simplistic. Other factors can influence body composition. Among these are genetic predispositions to gaining weight, especially fat weight. Jean Mayer, who founded the Harvard School of Nutrition, once wrote that if you had one fat parent, your risk of also becoming fat was 40%. If both parents were obese, the risk rose to 80%. That was depressing to many who seemed doomed to be fat because of their genetic heritage. But what Mayer overlooked was that the eating and exercise habits of parents are often duplicated by the children, which would explain obese children sired from obese parents. However, later twin studies found that the heritability of obesity or the risk of gaining body fat was far lower than what Mayer conceived. The actual genetic risk for obesity is only about 3 to 5%. What counts is other factors, which can include hormones and other environmental factors.

A big debate among researchers who study obesity is the influence of various hormones in promoting body fat gains. Foremost among these are thyroid hormones and insulin. Many often blame their elevated body fat levels on a "slow metabolism." The implication is that they don't consume excessive calories, which would account for their higher body fat levels, but instead, they don't burn calories efficiently because of poor thyroid hormone output. The thyroid gland produces two primary hormones, T4 and T3, with the numbers standing for the iodine contained in the hormones. Thyroid hormones are a combination of the trace mineral iodine and the amino acid tyrosine. Contrary to popular belief, most people with higher body fat levels not only produce higher levels of thyroid hormones but in some cases, more than those with lower body fat levels. But thyroid problems can exist, and when they do, they can affect body fat composition because the thyroid . . .