A recent study found that restricted calories with exercise adversely affect bone health in mammals. The study is conducted by the UNC School of Medicine. It is published in the Journal of Bone and Mineral Research.
Maya Styner said that previous researchers kept mice in normal and high caloric conditions with exercise. They observed positive effects on bone health.
However, Styner and her team found the opposite results in the case of restricted calories in the diet.
Styner’s research focused on the fat content in the bone marrow of mice. Researchers suggest that fat in bone marrow is harmful to mammals including humans. The reason is it weakens the bones. Less fat in bone indicates better bone health.
The previous studies focused on the effect produced in bone marrow fat due to caloric consumption. They observed the effect along with the role of exercise. In obesity, the amount of bone fat increases with excess caloric intake.
Exercise decreased the fat in bone marrow in both obese and normal-weight mice. This resulted in the improvement of bone mineral density.
Effect of restricted calories on bone health along with exercise
The latest study identified the effect of restricted calories with exercise in bone marrow fat and overall bone health.
Styner took four groups of mice in her study. They included one group with regular diet intake. The second group ate a restricted-calorie diet. The third group included mice with regular diet and exercise. While the mice in the fourth group had a restricted-calorie diet with exercise.
Styner observed that the mice on a restricted-calorie diet without exercise lost weight but increased in bone marrow fat.
She said that we mildly restricted calories (30% less than regular diet calories). However, we found a considerable increase in fat marrow fat.
The mice group with a restricted-calorie diet also had decreased bone density. The reduced calories resulted in less bone mass.
An important point of the study is that researchers gave vitamin and mineral supplements to both groups of restricted-calorie diet. They did it to match their micronutrient intake with the nutrients obtained from a regular diet.
This indicates that the effect on bone health was due to caloric restriction, not the lack of micronutrients.
In the fourth group, Styner observed that the fat in bone marrow decreased due to exercise. However, it also resulted in decreased bone mass. Together with caloric restriction, exercise made the bones more fragile.
Effect of restricted calories and exercise on humans
For humans, a low-calorie diet can have adverse effects on bone health, even when consumed with enough nutrients. The effect is particularly significant when individuals exercise with a low-calorie diet.
It is particularly important for women because their bone health naturally decreases with the advancement in age. Therefore, a particular calorie intake together with an exercise routine can greatly influence bone health and strength.
The US Department of Agriculture (USDA) recommends a 2,000 calorie diet/ day for a moderately active woman (around 30 years). A 30% reduction results in a 1400 calorie diet per day. USDA recommends this low-calorie diet to women trying to lose weight at the rate of one pound per week.