A study reveals that thin people do not exercise more than the rest of us; rather, they eat less.
It has long been believed that naturally skinny people can eat whatever they want since they move more.
Researchers have discovered, however, that they move more and consume less.
They compared the diets and energy levels of 150 “super-lean” individuals with 173 normal-weight individuals.
During the two-week trial, naturally thin individuals engaged in 23% less physical activity and spent more time sitting or lying down. Additionally, they consumed 12% less food.
However, it was discovered that they had a faster resting metabolism, which may allow them to burn more calories at rest than the normal individual.
The study’s director from the University of Aberdeen, Professor John Speakman, remarked, “The results came as a complete surprise.”
When speaking with extremely thin people, it is common for them to claim they can eat whatever they want.
However, our research revealed that their actual caloric intake is significantly lower than that of those with a normal body mass index (BMI).
The study, which was published in Cell Metabolism, recruited naturally slender individuals with a mean BMI of 17.
A BMI below 18.5 is considered to be underweight, and the individuals in the study appeared to be naturally thin, with researchers ensuring that they were not on a diet, had not lost weight due to sickness, or had an eating disorder.
Surprisingly, 96 percent of these naturally thin individuals’ time was spent sitting or performing light physical exercise.
However, they appeared to consume much less food than those of normal weight, whose BMI was between 18.5 and 25 (the criteria for being overweight).
To determine if naturally slim people could eat anything they desired, researchers did not require them to keep meal diaries, which are prone to error, but instead computed their calorie intake based on how much energy they expended.
People’s energy consumption was determined by giving them water with heavy isotopes of hydrogen and oxygen every day.
These are measured in the urine because their rate of elimination in the body depends on the number of calories burned and converted to carbon dioxide.
Using this energy expenditure, assessed against physical activity, researchers conclude that naturally thin participants in the study consumed an average of 12% fewer calories than normal-weight adults.
But they were also fortunate in that they burned more energy while sitting still than normal-weight folks, indicating a faster metabolism.
In actuality, their metabolism was 22% greater than projected based on their amounts of body fat.
This was associated with increased thyroid hormone levels, which can help people feel less hungry and maintain a healthy weight.
The researchers are currently examining whether naturally slim people have a faster metabolism and more thyroid hormones due to their DNA, and have already identified certain genetic quirks that may explain how people avoid gaining weight.
There is evidence that approximately 1.7% of persons are underweight.
While some will have eating disorders or have lost weight due to disease, the majority of those who are underweight are perfectly healthy.
Other naturally thin people who were not a part of the study may be more active than those analyzed in the current study.
In contrast, the study’s participants tended to have lower levels of bad cholesterol than normal-weight individuals, indicating that naturally slim people can get away with less physical activity and a smaller caloric intake.
Dr. Sumei Hu, the co-lead author of the study from the University of Aberdeen, remarked, ‘It was a major surprise to me that the super-lean individuals were significantly less active than those within the normal BMI range.
I’ve always believed that lean individuals must be quite active to maintain their low body weight, but our findings indicate otherwise. Eating less is the key to keeping thin, a study finds.
