Exercising, restricting calories intake, supplying proteins – they are like the three standard steps if you want to lose weight or go for a workout. However, the process can be painful, your stomach groaning, your weight remaining, and your appetite better than ever.
A new reason for eating as you like when exercising has arisen: a new study shows how bones in mammals are negatively impacted by calorie restriction, and particularly by the combination of exercise and calorie restriction.
About the study
Fat in the bone is thought to be harmful to bones of mammals, including humans, because it makes bone weaker. Less fat is usually an indication of better bone health.
The latest study aimed to find out what happens to bone marrow fat and overall bone health when restricting calories in mice. The mice were divided into four groups:
A group on a regular diet (RD)
A group on a calorie-restricted (CR) diet
A RD group that exercised
A CR group that exercised
Mice in the CR group ate 30% less than those in the RD group.
For context in humans, according to the United Sates Department of Agriculture (USDA), a “moderately active” woman about 30 in age should consume 2,000 calories per day. A 30% reduction would consume 1,400 calories per day, which is the amount a woman should take if she wants to lose about one pound a week.
Researchers found that mice in the CR group lost weight, but also had an increase in bone marrow fat.
"This was mild caloric restriction, and we found a significant increase of fat in the bone marrow," the researcher Styner said. "This group also had a decrease in bone quantity—they had less bone overall due to the cut in calories."
Both CR groups were given supplements of vitamins and minerals to match the amount the RD group received from the extra food they ate. The result indicated that the effect on bone health was from calorie restriction instead of a lack of nutrients.
"Looking at this from a human perspective, even a lower calorie diet that is very nutritionally sound can have negative effects on bone health, especially paired with exercise," said Styner. "This is important for women to consider because as we age our bone health starts to naturally decline. Your calorie intake and exercise routine can have a great impact on the strength of your bones and your risk for break or fracture."