Editorial Note: Health and Wellness explored and explained the medical research on calorie restriction. However, the following information is not intended as medical advice and should not be construed as such. Individuals should consult their physicians and dietitians familiar with their health before making changes to their diets or exercise habits.
If your vision for your later years includes kayaking on a placid lake or besting your friends in Taboo – every, single, time – then cutting calories right now could affect whether that dream becomes reality, research shows.
An article published by the National Institute of Health included an emphatic statement about eating less to age well.
“Calorie restriction has been considered the most effective non-pharmacological intervention to counteract aging-related diseases and improve longevity,” read the abstract of the research that examined results from 40 calorie restriction studies. “This intervention has shown beneficial effects in the prevention and treatment of several chronic diseases and functional declines related to aging, such as Parkinson’s, Alzheimer’s, and neuroendocrine disorders.”
Across various studies involving humans and animals, researchers found that the effectiveness of reducing caloric consumption, without diminishing the nutritive value of their diet, varied depending on:
- Age when eating less began
- Percentage by which calories were reduced
- Length of time practicing calorie restriction
- Inclusion of exercise during periods of reduced calorie consumption
What’s The Science Behind It?
A research team at Yale University School of Medicine used data from individuals between the ages of 25 and 45 who were asked to reduce their caloric intake by 25% over two years. The reviewed sample set came from participants who reduced their calorie intake by an average of 14%.
Investigators noted two biological changes in the participants. First, their number of T-cells increased. T-cells, also known as T lymphocytes, are white blood cells that help stave off disease and may play a role in fighting cancer. The second observation involved inflammation.
Restricting calorie consumption changed immune cells and body fat gene activity, the team observed. Researchers also discovered a new gene that controls inflammation. Consuming fewer calories limited that gene’s activity.
Chronic inflammation causes tissue deterioration within the body. Several lifestyle choices, such as being obese, smoking, not exercising, drinking alcohol excessively and making poor food choices, can all lead to inflammation that can cause disease, according to Harvard Health.
“A growing body of evidence suggests that low-grade, chronic inflammation contributes to some of the nation’s leading killers, including cardiovascular disease, cancer, and type 2 diabetes, as well as Alzheimer’s disease, allergies and asthma, arthritis, anxiety and depression,” according to a 2023 Harvard Health publication.
Outcomes From Restricting Calories
Additionally, a review of studies conducted between 2010 and 2020 included data indicating that caloric restrictions improved the level of biomarkers associated with cellular health and DNA repair. That review of research evaluating calorie restriction also indicated beneficial effects on the cardiovascular system and a reduction in blood pressure.
As mentioned, the severity of calorie restrictions also affects health results. The percentage by which calories were reduced varied from 12% to 40% across studies. In some research involving humans, participants experienced anemia, weakness and irritability, as well as a loss of muscle mass and reduced bone density, all of which were connected to individual body traits and the degree to which they restricted calories.
Research continues on how calorie restrictions affect cognitive abilities and memory. In studies involving mice, when caloric consumption was reduced by 30%, the cognitive performance of the restricted mice was “significantly better” than mice that ate a standard diet.
