Can curbing your usual daily calorie intake by 10% improve health and longevity?
There is a saying: “The less you eat, the longer you live.” The rising rates of obesity have shown that Americans consume more than necessary, and cutting back on calories may be a smart move.
“People naturally gain about a pound a year, on average, beginning in middle age, so healthy weight needs to be a goal for older men,” says Vasanti Malik, a research scientist in the Department of Nutrition at Harvard’s T.H. Chan School of Public Health. “That is why being mindful of how many calories you really need — and perhaps cutting back some, an approach called calorie restriction — may help some men stay healthy and maybe even live longer.”
Less can be more
Federal guidelines suggest older men consume between 2,000 and 2,800 calories a day depending on their activity level. (See “Daily calorie levels for men ages 51 and older.”)
Calorie restriction can be a loose term, but generally it involves consuming about 10% to 15% fewer calories than your regular intake, but without reducing key nutrients, according to Malik. “This may help men lose excess weight by being smarter about food choices and portions.”
Ground-floor animal studies have shown that calorie restriction may help increase life span by slowing metabolism and increasing muscle mass. However, these findings have not yet translated to human studies. Still, calorie restriction may help with longevity in other ways.
A 2015 study published in The Journal of Gerontology: Medical Sciences looked at a two-year trial on calorie restriction called CALERIE. Researchers recruited 220 middle-aged adults, most of whom were moderately overweight, and divided them into two groups. One group was given goals of 15.5% weight loss in the first year, followed by weight stability over the second year. The approach was to reduce their calories to 25% below their regular daily intake.
This was an ambitious target, and the group only achieved a more realistic 12% calorie restriction. Still, the participants lost an average of 10% of their body weight in the first year, and best of all, maintained that weight over the second year.
In terms of specific benefits tied to longevity, the researchers found the group’s average blood pressure dropped by 4% and total cholesterol by 6% compared with the control group. There was also a 47% reduction in levels of C-reactive protein, an inflammatory factor linked to cardiovascular disease.
Levels of the thyroid hormone triiodothyronine (T3) dropped by more than 20% in the calorie restriction group. Some studies have suggested that lower thyroid activity may help the body age at a slower rate.
Beyond weight loss
It makes sense that calorie restriction helped overweight people lose weight, but it also may benefit normalweight individuals.
A study in the February 2016 Aging Cell also used information from the two-year CALERIE trial to explore how a -calorie-restriction diet may affect people with a body mass index of 25 (which is on the border between normal and overweight).
After two years, this group had lost, on average, about 11% of their body weight, and 71% of this was in the form of fat loss. The researchers also found that in these people, concentrations of insulin-like growth factor–binding proteins (IGFBP1) increased by more than 21% to 25%. Low levels of IGFBP-1 have been associated with aging.
Calorie restriction is about food sources as well as numbers. “It is not about cutting out food, but about monitoring your intake and ensuring you eat the right foods and in the right amounts, without depriving your body of key nutrients you need, like vitamin D, calcium, and iron,” says Malik.
Counting calories can be confusing and tiresome. Instead, be mindful of portion sizes and choose high-quality foods, such as whole fruits and vegetables as well as protein sources like fish, eggs, and poultry. In addition, limit or avoid refined grains and processed foods, suggests Malik.
For portion control, measure the single portion on the nutritional panel on the food’s label to get a visual image of a proper serving. “For example, seeing what a cup of cooked pasta looks like on your plate can give you a clearer idea of how much more you usually eat,” says Malik. “Often you can feel nourished and satisfied with less, when given the chance.”
Make sure you consult with your doctor before making any changes to your regular diet. Older men who have difficulty getting sufficient calories, and thus proper nutrients, and won’t benefit from unnecessary weight loss.
Daily calorie levels for men ages 51 and older
2,000 to 2,200 calories: Sedentary (only performs activities associated with typical day-to-day life)
2,200 to 2,400 calories: Moderately active (walks the equivalent of 1.5 to 3 miles a day at 3 to 4 mph)
2,400 to 2,800 calories: Active (walks the equivalent of more than 3 miles a day at 3 to 4 mph)
Source: National Institutes of Health.
Harvard Men’s Health Watch