Gut Organisms Could Be Clue in Controlling Obesity Risk

The international obesity epidemic is widespread, nondiscriminatory, and deadly. But do we really understand all of the factors underlying this alarming trend? The concept of energy balance (energy consumed = energy expended + energy stored) is undeniable, being driven by the first law of thermodynamics. Consequently, there is no contradiction that excessive calorie intake and plummeting levels of physical activity are largely to blame for our ever-expanding waistlines. However, scientists remain baffled as to why some individuals are particularly prone to becoming obese and if there is anything aside from lowering calorie consumption and increasing activity levels that can be done to prevent and/or reverse excessive weight gain in our most at-risk populations. Physiologists have long known that our intestines are brimming with live bacteria, some of which provide important substances (e.g., vitamin B-12) to their host. However, research conducted over the last decade suggests that these organisms, often referred to as intestinal microbiota, may play a far greater role in human health than previously imagined. One area of intense interest is the possibility that the mix of intestinal bacteria with which we are endowed might directly influence our risk for obesity. Obese individuals tend to have different microbial profiles in their intestines than lean individuals, and scientists have learned that the bacteria common to obesity may metabolize the food we eat in a way that allows us to harvest more calories from it and deposit those calories as fat. To determine whether altering one's bacterial profile can change obesity risk, researchers from the French Institute for Agricultural Research (INRA) transferred the intestinal bacteria of obesity-prone or obesity-resistant rats into the intestinal tracts of germ-free mice recipients, therefore having no innate gut microbiota. Some animals were fed a regular diet, whereas others were provided unlimited access to a high-fat diet. Food intake and weight gain were monitored for 8 weeks, and intestinal samples were analyzed for a variety of physiologic markers of metabolism and normal feedback mechanisms known to play a role in maintenance of energy balance. As hypothesized, mice that received intestinal bacteria from obesity-prone animals ate more food, gained more weight, and became more obese than those receiving microbiota from obesity-resistant animals. Animals with microbiota transferred from obesity-prone animals also exhibited changes in intestinal nutrient sensors and gut peptide levels, likely influencing how the animals responded to eating. The authors' conclusions are three-fold. First, they theorize that obese individuals, when given the opportunity to overeat, may harbor specific gut microbiota profiles that promote excess weight gain. Second, they propose that differences in gut microbes can be related to behavioral changes and increased food intake. Finally, they believe that the mix of microbiota you have may influence your ability to properly sense and respond to a meal. They hope to eventually find ways to manipulate the intestinal microbiota profiles of especially at-risk individuals so that they can more easily maintain a healthy body weight...more

Men with low testosterone face increased risk of obesity and diabetes

MEN with low levels of testosterone could be at greater risk of developing diabetes, a study has suggested. Researchers from Edinburgh University found low testosterone levels are linked to a resistance to insulin, the hormone that controls blood sugar levels. • Research shows low testosterone levels “instrumental” in onset of diabetes • Men with low levels of testosterone are more likely to become obese Testosterone is present throughout the body and low levels are associated with increased obesity, a known risk factor for developing type 2 diabetes. But scientists said the study provides evidence of increased risk “even when body mass is not affected”. Dr Kerry McInnes, from the university’s endocrinology unit, said: “We know that men with low testosterone levels are more likely to become obese and as a result, develop diabetes. “This study shows that low testosterone is a risk factor for diabetes no matter how much a person weighs. As men age, their testosterone levels lower. This, along with increasing obesity, will increase the incidence of diabetes.” The research team said the study is the first to directly show how low testosterone levels in fat tissue can be “instrumental” in the onset of the condition. They said the findings show that mice with impaired testosterone function in fat tissue were more likely to be insulin-resistant. However, they also reveal that insulin resistance occurs in mice when testosterone function was impaired regardless of body weight...more

Nighttime fasting may foster weight loss

In an age of long commutes, late sports practices, endless workdays and 24/7 television programming, the image of Mom hanging up her dish towel at 7 p.m. and declaring "the kitchen is closed" seems a quaint relic of an earlier era. It also harks back to a thinner America. And that may be no coincidence. A new study, conducted on mice, hints at an unexpected contributor to the nation's epidemic of obesity — and, if later human studies bear it out, a possible way to have our cake and eat it too, with less risk of weight gain and the diseases that come with it...more