12 . 10 . 2018
The Benefits of Calorie Restriction
and Intermittent Fasting
Nowadays, obesity and other metabolic diseases are increasingly frequent due to food abundance. Animal studies have shown that calorie restriction is linked to an increase in longevity, but long term and controlled interventions like these are difficult to replicate in humans, understandably.
Following a calorie restricted diet continuously is difficult and carries the risk of malnutrition. However, periods of fasting and therefore decreased calorie intake may offer similar physiologic benefits.
Fasting is an ancient practice associated with several religious traditions. Intermittent fasting consists of alternating periods of fasting with others of normal calorie intake. There are several forms of intermittent fasting, from alternate day fasting to, the most popular, time restricted feeding, where all meals are combined in a narrow window (6-8 of the 24 hours for example). All these modalities lead to decreased calorie intake and their benefits stem from that fact.
According to comparative human studies, continuous calorie restriction and intermittent fasting have similar effects on the markers of metabolic health. When combined with exercise, intermittent fasting has even more pronounced effects.
What are the benefits of intermittent fasting?
- Decreased weight and body fat percentage
- Decreased blood pressure
- Improved lipid profile – lowers total and LDL cholesterol; raises HDL cholesterol
- Increased insulin sensitivity and decreased diabetes mellitus type 2 risk
From a cellular perspective, periods of fasting function as a stress agent. In response to this stress (a similar process happens with physical exercise), the cell increases the production of certain substances (sirtuins, HSP’s, etc.) that increase its resilience. Fasting also promotes autophagy, which is a sort of “recycling” process, where the damaged organelles and debris are cleared from the cell, so that they don’t interfere with its function.
Is intermittent fasting safe for everyone?
No. Despite being an excellent tool to optimize metabolic health, its use is contraindicated in some situations. Some examples are: pregnant or breastfeeding women (the body develops a physiological insulin resistance at these times that should not be opposed); patients with hypoglycemic tendencies or chronic fatigue syndromes, in whom this additional stressor may not be well handled by the body.
On the other hand, for overweight, insulin resistant and diabetic patients (the hallmarks of metabolic syndrome), this intervention should be considered. It’s important to emphasize the importance of maintaining a long-term healthy diet, devoid of processed foods and rich in nutrients.
Ganesan K, Habboush Y, Sultan S. Intermittent Fasting: The Choice for a Healthier Lifestyle. Cureus. 2018;10(7).
Patterson RE, Sears DD. Metabolic Effects of Intermittent Fasting. 2017. Annual Review of Nutrition. 2017; 37:371-393
Golbidi S, Daiber A, Korac B, Li H, Essop MF, Laher I. Health Benefits of Fasting and Caloric Restriction. Current Diabetes Reports. 2017;17(12):123.