While limiting calories has been found to prolong life in most animals that have been studied, it’s not entirely clear why. However, that doesn’t mean there aren’t theories: some researchers posit reducing calories slows metabolism, making the body more energy efficient and reducing oxidative stress that causes cell damage.

This is good news for your pet rat, but can you also reap the rewards of calorie reduction? Maybe—a two-year study published in Cell Metabolism found limiting calorie intake was linked to reduced oxidative damage in humans. After an intensive screening process, researchers selected 53 healthy, non-obese adults, ages 33 to 46, that had been assigned to one of two groups: the first group included 34 participants given detailed dietary instructions aimed at reducing their calorie intake by 25% while maintaining adequate nutrient intake; the second (control) group included 19 participants instructed to eat normally. Participants visited a metabolic chamber to test their metabolic rates over 24 hours at the start of the study and three additional times. Researchers also measured the participants’ weight, body composition, and core body temperature, as well as levels of oxidative stress markers and metabolism-regulating chemicals such as thyroid hormones, adrenaline, leptin, and insulin. At the end of the study, they found that:

• On average, the calorie-restricted group reduced their calorie intake by 14.8% and lost around 20 pounds, while the control group maintained their calorie intake and gained around four pounds. Most of the weight loss was due to loss of fat.
• In the calorie-restricted group, resting metabolism was reduced beyond what could be accounted for by weight and fat loss. Specifically, they burned 80 to 120 fewer calories each day relative to their weight loss.
• Levels of oxidative stress markers decreased in the calorie-restricted group, but not in the control group. The reduction in oxidative stress was proportional to the degree of calorie restriction attained and the change in resting metabolism.

This study indicates that limiting calories not only leads to weight loss but may also provide metabolic benefits associated with better health and possibly longer life. If you’re interested in a calorie-restricted diet, remember the restrictions in this study were considered severe and the participants were closely monitored to ensure they were adequately nourished. Be sure to speak with your healthcare practitioner before you start any new diet to be certain you’re on the right path.

Source: Cell Metabolism