New Study Proves Dieting is Difficult For Those With Thrifty Metabolisms

Posted on May 15, 2015

Drs. Martin Reinhardt and Suzanne Votruba with carbon dioxide and oxygen analyzers

Traditional thinking says that weight loss is all about calories in and energy expended and that anyone can lose weight just be cutting calories and increasing exercise. But scientific studies are revealing that the traditional model for weight loss or gain is simplistic and inaccurate.

Scientists at the Phoenix Epidemiology and Clinical Research Branch (PECRB), part of the NIH’s National Institute of Diabetes and Digestive and Kidney Diseases, just proved that dieters with what they call the "thrifty" metabolism will lose weight slower and gain weight faster than people with the "spendthrift" metabolism -- even if they eat the exact same thing in the exact same amounts. The study will be published in the journal Diabetes. The study's lead researchers, Drs. Martin Reinhardt and Susanne Votruba, are pictured standing next to the carbon dioxide and oxygen analyzers in the above photograph.

The study took twelve obese women and men and checked them into the facility's metabolic unit. They use carbon dioxide and oxygen analyzers and a special, whole-room indirect calorimeter to measure each person's calorie expenditure after fasting for 24 hours. Then they overfed each person by 200% for 24 hours and tested their metabolisms again.

The study went on for six weeks. Everything was controlled by the researchers: the food, the level of activity, everything. The waste products from the test subjects was collected and tested. For six weeks, the researchers put the subjects on a 50% reduction of calorie diet. Some people lost weight faster than others. There was direct correlation: those who had the most efficient metabolisms gained weight more quickly and lost it more slowly, even accounting for age, sex, race and baseline weight.

The researchers say it is clear evidence that some people gain weight faster and lose weight slower than others, even if they eat the same things in the same amounts. "When people who are obese decrease the amount of food they eat, metabolic responses vary greatly, with a 'thrifty' metabolism possibly contributing to less weight lost," explains study author Susanne Votruba, Ph.D. Dr. Votruba says, "While behavioral factors such as adherence to diet affect weight loss to an extent, our study suggests we should consider a larger picture that includes individual physiology -- and that weight loss is one situation where being thrifty doesn't pay."

The researchers will next study lean people to see if they also have major differences in metabolic rate after fasting and after being overfed. The researchers hope to discover something that will help dieters take pounds off easier. Those with the thrifty metabolisms are able to live through a famine, which was a common occurrence for early humans. But in the modern world, the famine never comes. Consumers today have access to more food than humans have ever had, and the thrifty metabolism is now a hindrance rather than a help. But if a metabolism could be fine-tuned some how, keeping a healthy weight wouldn't be so difficult.

Photo: Enrique Diaz