According to the World Health Organization, worldwide obesity rates have tripled since 1975. In 2016, 39% of adults aged 18 years and over were overweight and 13% were obese. That equates to 1.9bn people.
The worldwide obesity epidemic and weight-related health issues, such as diabetes and cardiovascular disease, present a serious challenge to healthcare systems. And given the scale of the challenge, a significant body of research has emerged looking at strategies to help people lose weight.
However, according to Nestlé Research, ‘very little’ is currently known about why certain people are naturally resistant to weight gain in the first place.
Understanding the biological mechanisms that underlie this resistance to weight gain can help in providing solutions that work on long-term weight and health maintenance, Nestlé Research suggested.
“Understanding the natural reasons why some people are resistant to weight gain could provide new biological targets for weight management solutions and could ultimately allow more targeted nutritional approaches for obese people helping them in long-term weight maintenance,” said Dr Nele Gheldof, from Nestlé Research.
In the study, published in The American Journal of Clinical Nutrition, Nestlé Research scientists and clinical researchers from the Clinical Hospital at the University of St-Etienne, in France, identified the molecular aspects underlying the low body weight and fat of very lean people, known as Constitutional Thinness (CT) individuals.
The researchers conducted a clinical overfeeding study on 30 CT subjects and 30 controls (BMI 20–25 kg/m2) matched for age and sex.
After two weeks of baseline assessments, all participants consumed a bottle of Nestlé Health Science’s Renutryl Booster, which contains 72 g carbohydrates (48.5%), 30 g proteins (20%), and 21 g fat (31.5%) in addition to their usual food intake for two weeks. This provided a 600-kcal surplus to their normal diet.
The researchers then performed clinical and integrative molecular and transcriptomic analyses on white adipose and muscle tissues.
It found that CT individuals have distinct differences in their fat tissue.
Despite the fact that their fat cells are smaller, they contain more mitochondria, which produce energy in cells. The increased mitochondrial activity results in a higher fat burning rate and, ‘surprisingly’, also to higher fat synthesis.
These mechanisms lead to an increase in energy expenditure, and thus to resistance to weight gain, the researchers concluded.
‘Persistent low body weight in humans is associated with higher mitochondrial activity in white adipose tissue’
The American Journal of Clinical Nutrition
Authors: Ling Y, Carayol J, Galusca B, Canto C, Montaurier C, Matone A, Vassallo I, Minehira K, Alexandre V, Cominetti O, Núñez Galindo A, Corthésy J, Dayon L, Charpagne A, Métairon S, Raymond F, Descombes P, Casteillo F, Peoc’h M, Palaghiu R, Féasson L, Boirie Y, Estour B, Hager J, Germain N and Gheldof N