The difficulty of losing weight is determined by your personal constitution

For the first time, NIH researchers used experimental data from the laboratory to confirm the commonly believed view that people with a certain constitution lose less weight than others when restricting calories. The results of the study were published in the May 11 issue of the journal Diabetes.

Researchers at the PECRB, a branch of the NIH National Institute of Diabetes, Digestive and Kidney Diseases, the Phoenix Branch of Epidemiology and Clinical Research, used a metabolic unit measuring facility to study 12 obese men and women. Using a whole-room indirect calorimeter, which measures energy consumption based on air samples, the researchers were able to get baseline measurements of participants 'energy consumption. Participants fasted for the first day and were hospitalized for the next six weeks to receive a 50% reduction in calorie intake. After accounting for factors such as age, gender, ethnicity and weight baselines, the researchers found that during the caloric restriction period, those who lost the least weight had the most metabolic decline when fasting. Researchers called these people "frugal" metabolic groups. Compared with these people, those with "spendthrift" metabolism experienced the least decline in metabolic levels and the most weight loss.

"When obese people reduce the amount they eat, the metabolic response changes significantly, and this 'frugal' metabolism may help make up for the loss of weight," said Dr. Susanne Votruba, a PECRB clinical researcher and author of the study. "Although some behavioral factors, such as adhering to a diet, can affect weight loss to some extent, our research suggests that we should consider more comprehensively, including an individual's physiological conditions. Weight loss is a situation when 'frugality' does not work."

Researchers don't know whether the biological differences are innate or developed over time. Further research is needed to determine whether an individual's response to reduced calorie intake can be used to control weight gain.

"These findings confirm the idea that some obese people may have to put in more effort to lose weight because of differences in their metabolism," said PECRB Bo, PhD Martin Reinhardt, lead author of the paper. "But biological traits are not destiny. A balanced diet and regular exercise can also reduce weight over time."

More than one-third of American adults are obese. Complications of obesity include heart disease, type 2 diabetes and some types of tumors, some of the leading causes of preventable death.

"We can learn from this study that there may one day be a personalized plan to help obese people reach a healthy weight," said Griffin P. Rodgers, director of NIDDK. "This study represents the latest advance in NIDDK's growing understanding of obesity."