Prevent excess weight, regulate blood sugar and reduce the risk of chronic diseases by simply eating at fixed times, over a period of 12 hours, chrononutrition does wonders for your health.
Thanks to a sophisticated system of regulatory genes that are expressed cyclically, the biological clock allows the body to control blood sugar levels completely independently. On the other hand, when this circadian rhythm is disturbed (among night workers or when food consumption is spread over the whole day), this system becomes inefficient and the resulting fluctuations in blood sugar can, over time, affect the insulin production and lead to type 2 diabetes.
Pick up the pace
Studies indicate that a simple way to avoid metabolic disturbances is to restrict food intake for less than 12 hours. This new concept, called “time-restricted feeding”, is based on the fact that our species originated in Africa, near the equator, and therefore our metabolism evolved to operate optimally for roughly equivalent durations of day and night (12 hours each). Eating the total daily calories over a short period of time, such as 8 hours, followed by an 18 hour fast, therefore synchronizes food intake with the natural cycle of metabolism. A very simple approach, but one that is very effective.
Eating over a 12-hour period
A very large number of studies carried out to date in animal models indicate that this type of diet optimizes metabolic efficiency, helps maintain a healthy weight and prevents or delays the progression of several diseases, including atherosclerosis, diabetes, certain cancers, and neurodegenerative diseases.
To assess whether time-restricted eating can also cause beneficial effects in humans, a team of American scientists recruited obese volunteers (average BMI of 32) who presented with metabolic abnormalities characteristic of prediabetes (glycaemia and elevated fasting insulin levels, glucose intolerance, higher than normal glycated hemoglobin). Throughout the study, participants ate prepared meals, according to the directions provided to them.
In the first part of the study, lasting 5 weeks, the volunteers ate their three meals over a 12-hour period, and a host of biochemical parameters (glycemia, insulin, blood lipids) and vital signs ( blood pressure) were measured at regular intervals. After an interval period of 7 weeks, during which the participants could eat as they wished, they undertook the second part of the study which consisted of eating exactly the same meals as in the first, but this time on a period of 6 hours.
Insulin levels and blood pressure regulate themselves
The results are very interesting: even though the participants consumed the same number of calories in both arms of the study and therefore did not lose weight, the simple act of restricting food intake over a longer period of time reduced has measurable repercussions on several metabolic parameters: the level of insulin drops drastically, in particular in people who presented hyperinsulinaemia at the start of the study, a drop linked to a marked improvement in the response of the organs to this hormone.
Blood pressure is also greatly affected, with a decrease in systolic and diastolic pressures of about 10 mm Hg, a drop comparable to that caused by antihypertensive drugs. Since hypertension and hyperinsulinemia are major risk factors for cardiovascular disease, these results illustrate how the simple act of eating for a shorter period of time can have a major positive impact on health.
With the omnipresence of food in our environment (and the many advertisements encouraging people to eat), it has become common to snack on a small snack at any time, even until late at night. The results of this study show, however, that to stay healthy, we must respect the complexity of our biological clock and avoid eating anything at any time.
Melkani GC and S Panda. Time-restricted feeding for prevention and treatment of cardiometabolic disorders. J. Physiol. 2017; 595: 3691-3700.
Sutton EF et al. Early time-restricted feeding improves insulin sensitivity, blood pressure, and oxidative stress even without weight loss in men with prediabetes. Cell Metab. 2018; 27:1212-1221.e3.