VIENNA, Austria — Many people like to work out and burn fat in the heat, but a study finds a really chilly day might be better for your weight. Researchers from the Medical University of Vienna say cold temperatures help the body increase vitamin A levels in humans. Their study finds this helps transform “bad” white fatty tissue into “good” brown tissue which is better for fat burning.
Lead researcher Florian Kiefer says converting white adipose tissue into its brown counterpart usually triggers more energy consumption in humans. Most mammals, including people, carry these two varieties of fatty depots. White fat makes up more than 90 percent of the body’s fat depots in people; typically sitting in the abdomen, bottom, and upper thighs. The body stores excess calories in these areas when obesity is setting in. Brown fat however, burns energy and also generates heat.
The study looked at how the combination of cold weather and vitamin A production might produce a unique therapy for obesity. Researchers say most of the body’s vitamin A reserves reside in the liver. When it’s cold, the body springs into action by stimulating vitamins A’s distribution towards adipose tissue. By triggering this response to cold weather, researchers witnessed the “browning” process turn adipose tissue into more easily burned off fat.
‘Critical vitamin A is transported to right cells at the right time’
Researchers reveals vitamin A and its blood transporter, retinol-binding protein, travel into fatty areas when the body feels cold. Mice, being another mammal, also experience this fat transformation.
Study authors experimented to see what happens when the vitamin A transporter is blocked. Using genetic manipulation, the researchers discovered that both cold-induced vitamin A production and fat “browning” is stifled in mice who don’t have retinol-binding protein in their bodies.
Tests on humans reveal when vitamin A does get to these depots white fat cells express brown fat cell characteristics. This leads to increased metabolic activity and energy consumption.
“As a consequence, fat oxidation and heat production were perturbed so that the mice were no longer able to protect themselves against the cold,” Kiefer explains in a university release.
“Our results show that vitamin A plays an important role in the function of adipose tissue and affects global energy metabolism. However, this is not an argument for consuming large amounts of vitamin A supplements if not prescribed, because it is critical that vitamin A is transported to the right cells at the right time,” the researcher from MedUni Vienna’s Division of Endocrinology and Metabolism cautions.
“We have discovered a new mechanism by which vitamin A regulates lipid combustion and heat generation in cold conditions. This could help us to develop new therapeutic interventions that exploit this specific mechanism.”
The study appears in the journal Molecular Metabolism.