Intermittent fasting

Posted on: 02/24/2025

Intermittent fasting (IF) is a dietary trend that has gained in popularity in recent years. It simply involves alternating periods of food restriction with periods of more conventional eating. Numerous studies have demonstrated the positive effects of intermittent fasting on both weight loss and health. So it's hardly surprising that this method has been practiced since the dawn of time by certain cultures for health or spiritual reasons. There are many different ways of practicing intermittent fasting, depending on the objective. For example, "leangains" is a type of intermittent fasting perfectly suited to bodybuilding. What is intermittent fasting? What are its benefits? How do you go about it? And how do you manage it when you're an athlete ?

What is intermittent fasting ?

Intermittent fasting is not at all complicated. You need to alternate periods of normal eating with periods of no food at all. There are several types of intermittent fasting, the 16/8 method and the 5:2 diet being the most popular. Basically, you'll fast for at least 16 hours and eat for only 8.

Do you think that's unusual? Well, not really! Yes, the typical day starts with breakfast and ends with dinner. The classic 3 meals a day, with optional snacks. The truth is, our bodies haven't been used to this since the dawn of time. In fact, our ancestors fasted for a good part of the day before eating. So it's a natural way of eating.

Most diets tell you what to eat, what not to eat and how much to eat. Intermittent fasting is completely different, and focuses not on what you should eat, but when you should eat it. Following a diet can be complicated. Counting calories, avoiding this or that food or food category, respecting quantities and so on. It can all be frustrating in the long run. And it's no wonder that many people abandon this approach. When counting, tracking and planning become too difficult, intermittent fasting can be a good alternative. It allows you to limit your calorie intake during certain periods.

On the other hand, while this dietary approach may simplify your nutrition, it can also disrupt your sporting activities. Eating provides energy, and if you suppress this for most of the day, your sporting sessions are likely to suffer, which can be tricky if your aim is to perform or build muscle mass. But nothing's impossible if you have the right method.

Young intermittents are good for your health !

The benefits of intermittent fasting are mainly related to weight loss. This "diet", which isn't a diet, helps you to be in a calorie deficit, which promotes weight loss. Some studies suggest that intermittent youth helps regulate blood sugar, improves insulin resistance and reduces the risk of cardiovascular disease. Research even suggests that intermittent fasting can improve longevity.

This fasting method improves health, notably by delaying cell ageing, by modifying the way the body functions. The increased production of adrenalin and noradrenalin means that after around 12 hours of fasting, you're more alert, able to concentrate and think more effectively. This is an adaptation mechanism that enabled our ancestors to hunt efficiently despite fasting.

Intermittent fasting has also been shown to increase resistance to disease and extend lifespan. Indeed, when food is abundant, the body tends to take the easy way out when certain cells are damaged: it destroys them and then replaces them, accelerating aging. During a period of caloric restriction or intermittent fasting, the body undergoes stress and repairs cells instead of destroying them. As this process is less energy-intensive, it improves longevity by limiting the risk of bad DNA copies, which can occur when a cell is destroyed and then rebuilt. This is why fasting can be said to be good for your health.

Intermittent fasting also improves glycemic control, reduces insulin resistance and improves glucose tolerance (carbohydrates are more rapidly eliminated from the blood).

It's important to remember, however, that this is not a miracle diet. To lose weight, you still need to reduce your calorie intake and watch your diet carefully, just as you need to increase your total calories to gain muscle.

It should be noted that the body takes 1 to 2 weeks to adapt to this new lifestyle, so it needs this learning time to perfect its use of energy reserves.

Are there any risks to intermittent fasting ?

This protocol is practised by skipping breakfast, or even lunch, which is against "modern official recommendations". However, our ancestors didn't have fixed mealtimes; they had to eat when they had the opportunity, which forced them to go through periods of fasting. Recent studies have highlighted the efficiency of the human body's ability to function in times of fasting, notably by releasing greater quantities of catecholamines, a group of hormones that includes adrenalin and noradrenalin, enabling the body to stay sharp during the fasting period. This was essential for survival, as the hormone release made man more efficient at hunting. Even if our eating habits have changed since then, we're still the same - our bodies haven't evolved since then.

Nor is there any risk of hypoglycemia, as might be feared. After the first few days of adaptation, the body learns to make better use of its fat reserves.

Nevertheless, some people with eating disorders may aggravate these by following intermittent fasting. Long periods of fasting can lead to fatigue, loss of concentration and, in some cases, reduced performance. It can also disrupt the hormonal system in some women. Intermittent fasting is not recommended for pregnant women, children, adolescents, the elderly, people with cancer or heart disease.

Why do intermittent fasting when you're building muscle ?

As we've seen, intermittent fasting involves fasting for at least 16 hours and eating for just 8. 8h00. It's not just a diet for weight loss or health, it can also be used to build muscle. It all depends on the calorie intake you're going to have during the eating period.

Many bodybuilders fear that their muscles will melt if they don't respect the law of one meal every 3 hours. It's a myth! Many athletes who have tried it are here to testify. If you follow a specific protocol, you can even train on an empty stomach. Intermittent fasting is feasible for both athletes and non-athletes, for fitness, slimming or health purposes.

This type of nutrition will enable you to improve muscle growth, boost fat loss, get lean while enjoying your food, or gain mass while limiting fat gain. But from a more global perspective, we can also talk about the benefits of fasting for your body's overall health.

The Leangains protocol

Leangains is a protocol based on intermittent fasting adapted to bodybuilding. It adapts meals to your training schedule to optimize muscle gain without fat gain. The Leangains protocol was developed by a coach with a view to optimization. Its approach consists of 16 hours of fasting for 8 hours during which you can eat, an optimal approach for muscle development and the social aspect.

Leangains protocol: 1 meal before weight training and 2 afterwards

The Leangains protocol of a single meal before bodybuilding training is the most common for students, and involves eating a meal representing 20-25% of the day's caloric intake 2 to 3 hours before training. It should be made up of an ideal ratio of proteins and carbohydrates, e.g. 40-50g of protein for 50-60g of carbohydrates, and as little fat as possible.

Within an hour of training, the largest meal of the day should be eaten. After a workout, the body is very demanding in terms of nutrients, and eating the largest meal of the day will help to build or maintain muscle mass.

Finally, the last meal allows you to reach your desired calorie total, enjoy the social aspect of the meal and fill your stomach before going to sleep, which helps most people sleep better.

Example of a Leangains menu with 1 meal before and 2 after :

Example of a Leangains intermittent fasting maintenance menu for a person with a caloric requirement of 2500 KCal:

Training day protocol :

First 12-hour meal: 500 calories (equivalent ratio of proteins to carbohydrates)
Weight training from 3 to 4 p.m
Second meal 16:30: 1500 calories (very rich in carbohydrates and proteins)
Last meal at 7:30 pm: 500 calories (slow protein source)
Fasting resumes at 8 p.m

Day off :

First meal 12h: 1000 calories (very high in protein)
Second meal 4pm: 800 calories
Last meal at 7:30pm: 700 calories. (slow proteins)
Fasting resumes at 8 p.m

For dry mass gain, add 20% more calories on training days and reduce rest day calories by 20%.

Leangains protocol: 2 meals before the workout and 1 after:

In the second Leangains protocol, more often used by people with jobs, two meals will take place before training:

The first meal represents around 20% of the day's total calories,
The second meal, also eaten 2 to 3 hours before training,
Finally, in the hour following training, the biggest meal of the day will be eaten.

During training days, the emphasis will be on carbohydrates, to promote recovery, and on essential fats, particularly omega-3s.

Lipids should be drastically reduced, and proteins and carbohydrates should predominate. As with a normal diet, count 1.5 to 2 grams of protein per kilo of body weight, and the remainder in carbohydrates. Slow-digesting proteins should be taken with the last meal of the day.

On rest days, the emphasis will be on lipids, so carbohydrates will have to be reduced. On rest days, carbohydrates should not exceed 100g, while proteins should always be eaten in large quantities.

The first meal should be the most important (around 40% of calorie intake). When dieting, it's advisable to eat plenty of protein for its satiating power and the difficulty the body has in converting it into fat. You can therefore increase your protein intake to 2.5-3g per kilo of body weight. Be sure to eat plenty of vegetables to maintain acid-base balance.

When building "dry mass", i.e. fat-free muscle, you'll need to increase your calorie intake by +20% on training days and -20% on rest days. So you'll be eating significantly more on training days than on rest days.

Finally

The key to safe intermittent fasting is to listen to your body. If you feel dizzy after getting on the treadmill, or weak during a workout, and this persists over the course of several sessions, review your plan. If necessary, ask someone to accompany you.

Having used this method, I've seen that it works. After a difficult start - having been fed 5 or 6 meals a day - my body adapted. My mind was sharper during the day, I had more energy to spare, my physique was drier, I was more congested during the session and my performance didn't really drop in the long term. This type of diet is perfect if you're suffering from weight problems, want to lose weight or have trouble eating in the morning. If you need to eat a lot to gain mass - because of a fast metabolism - you may need to switch to something else.

But remember, the body is equipped with everything it needs to gain muscle under these conditions. Our ancestors developed this genetic heritage over thousands of years, and it remains within us. It's just waiting to be reactivated !