Many people trying to lose pounds have seen their diet stall after some weight loss. New research shows how the body’s metabolism slows down as a way to reduce the amount of calories burned.
Analysis of data from 65 dieting white and black women aged 21-41 revealed that their bodies were able to adapt to burning 50 calories less per day on average. Some women who were initially overweight or obese adapted to lose weight to use hundreds of calories less per day, according to a report released on Thursday for obesity.
This “metabolic adaptation” is the response to weight loss by reducing the resting metabolic rate, the number of calories needed to keep important systems such as the heart and lungs functioning.
“Metabolic adaptation during weight loss can make it difficult for people to reach their goals,” said Catia Martins, an associate professor of nutrition at the University of Alabama at Birmingham, the lead author of the study. “This study found that people with high metabolic adaptation take longer to reach their weight loss goals.”
In this case, all women were trying to reach a body mass index (BMI) of 25, just above what is considered a normal or healthy BMI range of 18.5 to 24.9.
Martins and her colleagues found that for every 10 calories of resting metabolic rate, the diet took a day longer.
“There was a woman whose resting metabolic rate dropped by nearly 700 calories, which means it takes another 70 days, or about two months, to reach her weight loss goal compared to someone who has no metabolic adaptation. That’s what Martins said. Said.
To find out more about how a woman’s resting metabolic rate changes during a diet, Martins and her colleagues reanalyzed data from two early studies at the University of Alabama at Birmingham, ROMEO and JULIET. .. Researchers focused on patients who are losing weight on diet alone, with up to one day of exercise per week.
During the study, all volunteers were given a daily diet of 800 calories until they reached their weight loss goal. At that point, many measurements were made, including resting metabolic rate.
Martins and her colleagues determined that 64 percent of women were completely obsessed with diet. Overall, women lost an average of 12.5 kg (27.6 pounds) in an average of 22 weeks. When researchers explained factors such as dietary adherence, they found that the greater the change in resting metabolic rate, the longer it took women to reach their weight loss goals.
“People who are experiencing many metabolic adaptations experience weight loss plateaus and struggle to lose their last pound,” Martins said.
Exercise helps to resume weight loss
This study does not investigate whether changes in resting metabolic rate can be avoided. Martins said he thinks adding exercise as well as weightlifting might help. Another strategy, she said, was to take a short break from the meal.
“Once a person is really stable for a while (probably two weeks is enough), it’s no longer effective and you can resume your diet,” she said.
Dr. Leka Kumar, an associate professor of endocrinology, diabetes and metabolism in New York’s Weil Cornell Medicine, said there are other metabolic challenges to losing weight.
“Researchers have separated one aspect of metabolic adaptation,” said Kumar, who was not involved in the new study. “But the important thing is that it’s not just the resting metabolic rate that poses a challenge to people trying to lose weight. There are many hormones, such as ghrelin and leptin, that go the wrong way in weight loss. . “
The study “supports what people see in their own experience and what clinicians see in patients, not about willpower,” Kumar said. “As you lose weight, it becomes more and more difficult to reach your weight loss goals.”
The brain interprets the loss of calories as a danger to the body and is a sign that famine may have begun, Kumar said. “It’s true no matter how it’s achieved, whether it’s a diet or weight loss surgery.”
