Long term calorie restriction can harm your longevity, rather than help.
Calorie restriction is often recommended by health experts, particularly carbohydrates and even protein recently.
While short term calorie restriction can be beneficial for various reasons, a chronic calorie deficit can make you prematurely frail and increase likelihood of premature death.
The calorie in, calorie out theory fails to account for your body’s thermostat, the thyroid. Your thyroid doesn’t want you to run out of energy and die, so it turns down metabolism when you eat less. This means you can gain weight on half the calories while lacking the fuel your body needs to maintain youthful biology.
Should you still cut carbohydrates?
Just the bad ones. Cutting quality carbs (whole grains, fruits, vegetables, beans) may impair mitochondrial function and metabolic flexibility. Low carb diets are often justified by theoretical models and mouse studies, while observational studies in humans show the lowest mortality group ingesting a whopping 40-55% carbohydrate diet.
Not all weight loss is equal.
Losing weight can be a bad thing if you are becoming frail. Gaining weight can be a good thing if you are getting stronger.
So forget about your weight, focus on body mass composition (ration of muscle to fat) and get plenty of exercise to get your VO2 max as high as possible. It’s almost impossible to overdo moderate exercise (40-60% max heart rate) but keep vigorous exercise (70-90% of max heart rate) under 75 minutes per week.
The key to longevity is avoiding frailty in your 70s and 80s. That starts now with plenty of healthy calories and exercise.
Bon appetit!