A new hormone has been discovered in the fight against obesity. This one mimics the effects of exercise and would benefit those on a high-fat Western diet in not only losing weight but also restoring insulin sensitivity.

The USC Leonard Davis School of Gerontology team injected the hormone MOTS-c into mice fed a high-fat diet, which typically causes them to grow obese and develop resistance to insulin.

The injections not only suppressed both effects in mice, they also reversed age-dependent insulin-resistance, a condition that precedes diabetes.

Hormones act as the body's signals, triggering various responses. The newly discovered hormone, "MOTS-c," mainly targets muscle tissue and restores insulin sensitivity, counteracting diet-induced and age-dependent insulin resistance.

"This represents a major advance in the identification of new treatments for age-related diseases such as diabetes," said Pinchas Cohen, dean of the USC Davis school and senior author of the study.

The research findings appear in Cell Metabolism.

MOTS-c is unique as it is encoded in the DNA of mitochondria — the powerhouses of cells that convert food into energy.

Most other hormones are encoded in the DNA of the cell nucleus.

New light

"This discovery sheds new light on mitochondria and positions them as active regulators of metabolism," said Changhan Lee, assistant professor at USC Davis and lead author of the study.

Though the experiments on MOTS-c have been performed on lab mice, the molecular mechanisms are similar in all mammals, including humans.

Lee and Cohen collaborated with colleagues from the USC school as well as the David Geffen School of Medicine at UCLA and the National Institutes of Health.

A recent University of Wyoming study had shown a similar approach to induce weight loss without the need to restrict calorie intake by using capsaicin found in chili peppers.

Dietary capsaicin may stimulate fat burning by activating its receptors, which are expressed in white and brown fat cells, suggested that study.

More than 2.1 billion people in the world are overweight or obese, with the figure set to rise to include nearly half of the population by 2030. A recent report had shown that the burden of obesity in the UK could beat the total costs of war and terrorism.

Obesity increases the risk of a host of disorders including stroke, high blood pressure, diabetes, cancer and gall bladder diseases.