National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
The NIDDK Recent Advances & Emerging Opportunities is a compendium that highlights examples of the many research advances published by NIDDK-funded scientists and their colleagues in the most recent fiscal year, along with the technologies that made these achievements possible. This compendium also includes a section devoted to recent advances in obesity research at NIDDK.
This section provides examples of recent scientific advances from NIH-sponsored research, and is not intended to be a comprehensive list.
For the first time in a lab, researchers found evidence supporting the commonly held belief that people with certain physiologies lose less weight than others when limiting calories. They studied 12 men and women with obesity in the NIDDK Phoenix Epidemiology and Clinical Research Branch metabolic unit. Using a whole-room indirect calorimeter—which allows energy expenditure to be calculated based on air samples—researchers took baseline measurements of the participants’ energy expenditure in response to a day of fasting, followed by a six-week inpatient phase of 50% calorie reduction. They found that the people who lost the least weight during the calorie-reduced period were those whose metabolism decreased the most during fasting. Those people have what the researchers call a “thrifty” metabolism, compared to a “spendthrift” metabolism in those who lost the most weight and whose metabolism decreased the least. The results corroborate the idea that some people who are obese may have to work harder to lose weight due to metabolic differences. These findings may one day enable a more personalized approach to help people who are obese achieve a healthy weight.
It's normal for most women to gain weight during pregnancy, but gaining too much weight can pose serious health risks for both mother and baby. These risks are greater for women who are already obese when they become pregnant. Researchers helped obese women limit their weight gain during pregnancy by asking them to follow a healthy diet based on the Dietary Approaches to Stop Hypertension (DASH) eating pattern, which is high in fruits and vegetables and includes lean meats, lean proteins like chicken, fish, and low-fat beef, as well as whole grains. Participants were also asked to reduce their consumption of sweets and sweetened drinks and to track their dietary intake by keeping daily food records. Women in this intervention group gained significantly less weight than women in the control group, who received no advice or weight monitoring. The intervention group was also less likely to have large-for-gestational-age babies (those bigger than 90 percent of the babies of the same gestational age and gender), who are at increased risk for various health conditions. According to the study's lead author, Dr. Kim Vesco of the Kaiser Permanente Center for Health Research in Portland, Oregon, an important next step would be to work within the health care system to implement these beneficial strategies.
Overweight and obese adults who drink diet beverages consume significantly more solid-food calories—particularly from snacks—than those who drink sugary beverages. The findings highlight the challenges in using diet beverages to help control weight. Diet beverage use has skyrocketed in recent decades. It's now a common weight control strategy. It might make sense to think that diet beverages would help you lose weight due to their lack of calories. But the body's mechanisms for maintaining weight are subtle and complex. Studies into how diet beverages affect weight control have found conflicting results. "The results of our study suggest that overweight and obese adults looking to lose or maintain their weight—who have already made the switch from sugary to diet beverages—may need to look carefully at other components of their solid-food diet, particularly sweet snacks, to potentially identify areas for modification," says the lead researcher on the study, Sara N. Bleich, Ph.D.
Gut microbes from lean people helped prevent mice from becoming obese—but only if the animals ate a healthy diet. This research could point the way to new treatments for obesity. The human gut harbors a complex community of microbes that affect many aspects of our health. Evidence, mostly from studies of rodents, suggests that the gut microbiota may play a role in the development of obesity. In earlier research, a team led by Jeffrey Gordon, M.D., at the Washington University School of Medicine showed that obese and lean human twins have clear differences in their gut microbial communities. Most notably, the communities from obese twins have less diverse bacterial species. In their new study, the scientists used a mouse model to further explore the role that gut microbes play in obesity and metabolism. The team took gut microbes from four sets of human twins in which one was lean and the other obese. They introduced the microbes of each twin into different groups of mice that had been raised in a previously germ-free environment. They then observed weight and metabolic changes in the mouse groups when fed the same diet. Mice populated with microbes from a lean twin stayed slim, whereas those given microbes from an obese twin quickly gained weight. The "lean" and "obese" microbes had different measurable effects on the body's metabolism. "These experiments show that eating a healthy diet encourages microbes associated with leanness to become incorporated into the gut," Gordon says. "But a diet high in saturated fat and low in fruits and vegetables thwarts the invasion of microbes associated with leanness. This is important as we look to develop next-generation probiotic cocktails composed of defined collections of naturally occurring human gut microbes as a treatment for obesity."
Researchers at the NIH have created and confirmed the accuracy of a mathematical model that predicts how weight and body fat in children respond to adjustments in diet and physical activity. While the model may help to set realistic expectations, it has not been tested in a controlled clinical trial to determine if it is an effective tool for weight management. The model evolved from one developed at the NIH in 2011 to predict weight change in adults. The model for children considers their unique physiology, including changes in body composition as they grow. “Obese children are much more likely to become obese adults, which makes achieving or maintaining a healthy weight early in life vitally important,” said NIDDK Director Griffin P. Rodgers, M.D. “This study suggests that we may need to approach weight management and obesity prevention differently in youth than in adults.”
A study in mice suggests that gastric bypass surgery may result in weight loss in part by altering microbes in the gut. The finding may lead to a better understanding of how microbes influence energy balance. Gastric bypass is a type of surgery used to treat severe obesity. In a procedure known as Roux-en-Y gastric bypass (RYGB), part of the stomach and small intestine are removed. The procedure results in significant weight loss as well as improvements in associated conditions such as type 2 diabetes. Decreased calories, however, can’t fully account for all these effects. The digestive tract is home to trillions of microbes, both helpful and harmful, that outnumber the body’s cells by 10 to 1. A team of researchers wondered whether some of the benefits of RYGB surgery might come from changes in digestive tract microbes. This research shows that the beneficial effects of RYGB surgery are due in part to changes in the gut microbial community.
People with serious mental illnesses such as schizophrenia, bipolar disorder, and major depression can lose weight and keep it off through a modified lifestyle intervention program, a NIMH-funded study reported. Over 80 percent of people with serious mental illnesses are overweight or obese, which contributes to them dying at three times the rate of the overall population. They succumb mostly to the same things the rest of the population experiences—cardiovascular disease, diabetes, and cancer. Although antipsychotic medications increase appetite and cause weight gain in these patients, they are not the only culprits. Like the general population, sedentary lifestyle and poor diet also play a part. Lifestyle modifications such as diet and exercise should work for these patients, yet they are often left out of weight loss studies. This study could usher in new forms of weight loss treatment for people with serious mental illness.
The improvement in cardiovascular health that results from quitting smoking far outweighs the limited risks to cardiovascular health from a modest amount of weight gained after quitting, reports a National Institutes of Health-funded community study. The study found that former smokers without diabetes had about half as much risk of developing cardiovascular disease as current smokers, and this risk level did not change when post-cessation weight gain was accounted for in the analysis. This study is the first epidemiological effort to directly address the health impact of the weight gain that many people experience following smoking cessation.
A protein associated with conditions of metabolic imbalance, such as diabetes and obesity, may play a role in the development of aggressive forms of breast cancer, according to new findings by researchers at the National Cancer Institute (NCI) and their colleagues. Metabolic imbalance is often caused by elevated carbohydrate intake, which can lead to over-activating a molecule called C-terminal binding protein (CtBP). This over-activation, in turn, can increase the risk of breast cancer. “Our new work suggests that targeting CtBP may provide a way of treating breast cancer and possibly preventing breast cancer,” said Kevin Gardner, M.D., Ph.D., head of NCI's Transcription Regulation Section, Genetics Branch. “Research should continue to focus on the link between obesity, CtBP and breast cancer. This will require more population-based studies and multidisciplinary teams of scientist to investigate these links.”