Intermittent Fasting (IF) or Time Restricted Eating (TRE): How to adopt it safely in order to stay in shape?

Fasting

9 Sept

Intermittent fasting can unfortunately be practiced irresponsibly, which can have serious health consequences. However, by respecting certain rules, it allows you to keep slim and trim without danger. Read on for some explanations!

IF or TRE involve alternating periods of eating with periods of not eating, while continuing to drink water or unsweetened beverages. Associated with a balanced diet, a recent study published on February 7, 2023 in the journal Cells found that IF reduce weight gain.

What are the different methods of IF?

Researchers from INSERM (the acronym for Institut national de la santé et de la recherche médicale, which means National Institute of Health and Medical Research) have studied the effects of IF/TRE, which one can practiced in three different ways:

alternate day fasting, consisting of eating only every other day,
the 5.2 diet, during which one eats normally 5 days a week, then limit her/himself to 500/600 kcal the other two days.
time-restricted eating (TRE), which restricts the daily time, during which, one can eat (a time slot of 10 hours maximum), in order to prolong the nighttime fast.

In all cases, the objective is to reduce the blood level of insulin, the hormone whose excess promotes weight gain and the development of chronic diseases, but also to burn fat reserves more easily.

Which intermittent fasting was the most effective?

Compared to a classic low-calorie diet, alternate day fasting or the 5.2 diet did not seem to cause more weight loss. TRE, on the other hand, appeared more effective, in particular because it was accompanied by a reduction in appetite, linked to changes in the hormones which regulate hunger. Other advantages were mentioned, even if they must be confirmed by studies using a larger group: limiting one’s eating periods over time seemed to improve the quality of sleep (which can influence weight), lower bad cholesterol ( LDL) as well as blood pressure.

What should one eat during IF or TRE?

There are no prohibited foods, which is a big advantage compared to most weight loss diets. TRE allows you to eat sweet treats without constantly having high blood sugar (hyperglycemia) levels and especially insulin (which is used to regulate blood sugar) responsible for storage, because the long nocturnal period of fasting causes it to fall permanently. There is no need to cut out fatty foods either, as fat can be burned during the time you do not eat. However, it is important to balance your meals to stay healthy.

Be careful not to fast for more than 14 hours

In studies demonstrating the benefits of TRE, the window for eating was limited to 10 hours instead of 14 hours or more (14 hours corresponding to the time between a breakfast around 7 or 8 a.m. and a late dinner). Without experience, by limiting your eating window to 6 or 8 hours, you may expose yourself to serious bouts of fatigue or even headaches caused by hypoglycemia (a blood sugar that is too low ). Furthermore you might suffer deficiencies when you skip your main meal and do not consume enough nutritious food including vegetables, starchy foods, fish, meat or eggs, healthy fats, dairy products etc. and may lack enough fibre, vitamins, minerals, omega 3s, proteins, healthy fats, etc. in your diet.

Maintaining a social life

When you live as a couple, with your family or have professional lunches, fasting every other day is often a “mission impossible”. On the other hand, to follow TRE over 10 hours, you simply need to organize your meals according to your lifestyle:

People who usually skip breakfast can have their midday meal from 11:30 a.m. to 12 p.m., plan a snack around 3-4 p.m. and sit down for dinner around 8:30-9 p.m.
Fans of breakfast can have it around 9:30 a.m., lunch around 1:30-2 p.m. and dinner at 7 p.m.

Remembering to hydrate well during fasting is also necessary

If you do not drink during the time when you are not eating, you will very likely be exposed to dehydration and its consequences: reduced intellectual performance, dry skin, constipation, risk of kidney stones or urinary infection.

You can alternate between still or sparkling water, vegetable broth, herbal teas, unsweetened tea or coffee, but skip sugary drinks (fruit juices, sodas, etc.) and alcohol.

What are the contraindications of IF/TRE?

IF/TRE is not suitable:

For children and adolescents, who are still growing,
Pregnant or breastfeeding women, so as not to interfere with fetal nutrition or milk production,
Elderly people or undernourished sick people, so as not to aggravate muscle wasting or reduce the effectiveness of immune defenses.

And even if you think you are in perfect health, it is always best to consult your doctor before starting.

Eating during the day is essential

To reduce insulin levels, IF/TRE must be practiced during the day. If you eat too late (after 10:00 p.m.), IF/TRE is no longer beneficial because insulin secretion is generally low at night and high carbohydrate consumption too close to bed time will lead to high blood sugar levels whilst you are asleep which can eventually lead to blood vessels, veins and arteries being damaged.