You are probably reading this article because you have heard about the calorie restriction diet as a path to the fountain of youth. To understand the relationship between the calorie restriction diet and longevity, we dissect the latest scientific evidence and reveal what is known what is not yet conclusive.

The calorie restriction diet, or caloric restriction diet, refers to a chronic low calorie regimen designed to minimize calorie intake while providing all the essential nutrients. The link between calorie restriction and longevity has been observed in many centenarians around the world. Scientists have also succeeded at extending lifespans of mice and monkeys by administering a calorie restriction diet.

Calorie restriction optimal nutrition will differ from person to person. At least in the initial stages, those undergoing the diet should be monitored by a medical professional or nutritionist experienced with the diet plan. The diet aims for a Body Mass Index of around 21. On average, this is a reduction of calorie intake by 30% for a typical adult American diet and up to 50% for some its devout followers.

For proponents of this diet, the historical evidence from human populations is typically offered as evidence, where lifespans are observed to increase on average in populations where typical diets have lower calorie intake than the standard American diet. Research on animals with calorie-restricted diets is also cited as evidence for increased longevity.

For critics of the calorie restriction diet, harmful side effects are often cited as a counter-argument. The permanent state of semi-fasting, semi-starvation is difficult to maintain without depriving your body of essential nutrients. The dangers of undergoing the diet without supervision and monitoring are of note.

What we know so far

To state the obvious, adherents of this diet are less likely die of heart disease, and this is the top cause of death globally. That in itself will increase average lifespans significantly. Aside from this clear benefit of weight loss, the following are a few less understood outcomes.

The role of oxidative stress

Adherents of the diet typically substitute calorie rich foods with low-calorie nutrient-rich vegetables to strategically counter the hunger. This substitution comes with increased antioxidants that play a large role in reducing oxidative stress.

Furthermore, oxidative stress under this diet is minimal to begin with because the body adapts to the lower calorie intake by entering a low metabolic state. This means that there are less oxygen by-products that undergo metabolism within cells to produce highly reactive oxidants, the very molecules that trigger a chain reaction of cellular damage and subsequent manifestation in numerous diseases: metabolic syndrome, Parkinson’s, Alzheimer’s, heart disease, inflammatory diseases, and gene mutations that lead to cancer.

Sugar where art thou?

Consuming low calorie nutrient-rich foods also means less there is less sugar in the diet. This has numerous health benefits that are too many to address in this article.

For starters, insulin levels are generally low, and insulin sensitivity is increased. This reduces the incidents of diabetes for those on calorie restricted diets. It also reduces the accumulation of triglycerides and cholesterol in the atherosclerotic plaques, which are caused by chronically elevated levels of insulin.

A recently concluded nine-year joint research project conducted by VIB, KU Leuven and VUB revealed a positive correlation between sugar and cancer. The study has huge implications on prescribed diets for cancer patients.

It is also likely that ketones are present in the blood when the energy deficit is not offset by increased consumption of carbohydrates. Ketones provide the necessary fuel for the brain when there is insufficient glucose. Ketones are also a clean burning fuel that do not leave behind the free radicals involved in creating oxidative stress.

The side effects

Hunger is one side effect that may not reduce lifespan, but it definitely makes us miserable. For most people who try this diet, it fails for one of three reasons:

  1. The body enters a low metabolic state and adjusts to the caloric deficit by consuming less energy. Dieters often complain of being cold, feeling fatigue and sleeping often;
  2. They get hungry, depressed, and irritable and become binge eaters, which in a low metabolic state and with higher insulin sensitivity makes weight gain much easier and faster than in a normal state;
  3. They get sick for any number of reasons due to deficiencies in certain nutrients, and they are forced off the diet.

Missing essential nutrients is the primary downside of undergoing this diet as a permanent lifestyle.

Where do we go from here?

When people first try calorie restriction, the biggest challenge is the craving for carbohydrates. This craving has been shown to be an addiction that takes time to overcome. It has to do with insulin resistance that develops over time, which elevate the levels of insulin in the blood that signal fat cells to mop up excess glucose. Most dieters end up binging or relapse out of the diet because they could not maintain it as a permanent lifestyle.

Sugar is also addictive but differently to insulin resistance. It affects the brain the same way narcotics do, and this is explained by the dopamine secretion in the brain when we consume sugar.

What we propose to explore is a less blunt instrument to solving this longevity puzzle. After all, one of the reasons we want to prolong our lifespans is to enjoy life, and it makes no sense to remove one of its most enduring pleasures. Food can still be enjoyed if we understand the relevant pathways that are involved in controlling disease and age-related illnesses.

In the next few articles, we will be taking a deeper dive into this blunt instrument to truly understand the relationship between the calorie restriction diet and longevity.


Kemp, R. 1963. “Carbohydrate Addiction.” Practitioner. Mar; 190: 358-364.

Seyfried, B. T., M. Klebish, J. Marsh, and P. Mukherjee. 2009. “Targeting Energy Metabolism in Brain Cancer Through Calorie Restriction and the Ketogenic Diet.” Journal of Cancer Research Therapy. Sep; 5 (Suppl 1): S7-S15.