At a Glance
- People with obesity who reduced their weight by 5% had improvements in metabolic function in many tissues, including fat, liver, and muscle.
- Further weight loss of 10 to 15% resulted in some additional improvements.
More than 1 in 3 Americans is obese. Obesity is a risk factor for many diseases, including type 2 diabetes and heart disease. These health issues stem from a range of underlying metabolic abnormalities that affect the liver, pancreas, muscle, fat, and other tissues.
Most treatment guidelines recommend that people who are overweight or obese aim to lose 5% to 10% of their weight to achieve improvements in health. A team led by Dr. Samuel Klein at Washington University School of Medicine in St. Louis set out to characterize the metabolic benefits when people with obesity lose 5% and more of their weight. The study was supported in part by NIH’s National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and other NIH components.
The scientists randomly assigned 40 sedentary people with obesity to maintain their body weight or to go on a diet to lose 5% of their body weight, followed by targets of 10% and 15%. Participants averaged 44 years of age with a body mass index (BMI) of 38 (average weight of about 235 pounds). The participants didn’t smoke or have diabetes. The findings appeared online on February 22, 2016, in Cell Metabolism.
People in the weight loss group consumed a low-calorie diet with 50-55% of energy as carbohydrate, 30% as fat, and 15-20% as protein. They were provided with weekly diet and behavioral education sessions.
Nineteen participants achieved the initial target of 5% weight loss (average of 12 pounds) after about 3.5 months. The researchers found that these people had significantly decreased body fat, including abdominal fat and fat in the liver. They had decreased plasma levels of glucose, insulin, triglycerides, and leptin, which are risk factors for heart disease and diabetes. They also showed improved function of insulin-secreting β cells, as well as the ability of fat, liver, and muscle tissue to respond to insulin.
Markers of inflammation are elevated in people with obesity. The researchers, however, found no changes in systemic or fat tissue markers of inflammation with 5% weight loss.
Nine of the participants reached the subsequent targets, achieving about 11% weight loss (at about 7 months) and 16% loss (at about 10 months). The decreases in fat mass, plasma insulin, leptin, and triglyceride concentrations continued in tandem with the weight loss. These participants showed continued improvements in β cell function and in insulin sensitivity in muscle. Insulin sensitivity in liver and fat tissue, however, didn’t improve further with weight loss beyond 5%.
“Our findings demonstrate that you get the biggest bang for your buck with 5% weight loss,” Klein says. “If you weigh 200 pounds, you will be doing yourself a favor if you can lose 10 pounds and keep it off. You don’t have to lose 50 pounds to get important health benefits.”
The study wasn’t designed to determine whether these effects are sustained for longer periods of time. Further research will also be needed to determine whether people with diabetes have the same types and patterns of metabolic adaptations following progressive weight loss.