Laboratory studies of Trusted Source of animals, including rats, fruit flies, worms, and mice, show that those fed a calorie-restricted diet may live up to twice as long as those with an unrestricted diet.
Now, a team led by researchers from Yale University has investigated the effects of calorie restriction in people. Their findings, which appear in Science, may eventually lead to new ways to extend healthy life.
In animal studies, calorie reductions of 40% are common. However, as the authors of the new study explain, this affects growth, reproduction, and immunity Trusted Source. In the human study, calories were reduced by only 14%.
Unlike many weight loss diets, a calorie-restricted diet involves small reductions of habitual calorie intake Trusted Source over a long period. People usually lose some weight, but this is not the main aim of calorie restriction.
The researchers set out to investigate whether calorie restriction had similar health benefits in people as they did in other animals. They also wanted to identify any mechanisms behind these benefits.
Healthy adults:
Over 2 years, the team assessed just over 200 people, aged 21–50 years. All were participants in the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy clinical trial.
All the participants had a body mass index of 22.0 to 27.9, putting them in the healthy, non-obese category.
The calorie trial had already shown a reduction in cardio metabolic risk factors Trusted Source, involving cholesterol levels and blood pressure, in this group.
Kristin Kirkpatrick, a registered dietitian nutritionist at the Cleveland Clinic, told Medical News Today:
“The data presented in the study was very interesting. There have been multiple research studies on calorie restriction and lower carbohydrate profiles that are important to consider. The addition of this research is beneficial to advancing and supporting other findings.”
Effects on the thymus:
The researchers looked at the effect of calorie restriction on the thymus. This gland, situated in the chest, just above the heart, is part of the immune system. The thymus produces T cells — white blood cells that are essential for fighting infections.
Hormones released by the thymus inhibit the aging process. As people age, their thymus becomes fatty and smaller, and it produces fewer T cells. Older people are more susceptible to infections because of this reduced immunity.
The scientists performed MRI scans of the participants’ thymus glands. They found that those with calorie-restricted diets had greater functional thymus volume than those with unchanged diets.
The thymus glands of the restricted diet group were also less fatty and produced more T cells than those of the unrestricted diet group.
Although the thymus was being rejuvenated, there were no changes to the immune cells that the gland was producing.
You must be logged in to post a comment.