Weight loss: what's the best time for carbohydrate intake?

Sérgio Veloso


When your goal is to optimize your physique, the moment when you consume a certain nutrient can influence the result that is obtained. Particularly the timing of carbohydrate intake in the context of weight loss has been topic of discussion, and there are a lot of myths and scientifically unfounded ideas regarding this subject.

For starters, it's important to point out that as such, carbohydrates are not at all harmful to a well-defined and toned physique. The widely held idea that they may cause harm is actually a myth best put aside. Carbohydrate intake however should take place in the right amounts and at the right time, probably post workout.

After training, muscle tissue is more sensitive to insulin and more tolerant to carbohydrates. This means that after consumption, more carbs will find their way into the muscles to replenish the glycogen spent during the training session. Similarly, the oxidation of fatty acids becomes the predominant way to produce energy, thereby saving carbohydrates for the purpose of biosynthesis. Preparing the muscle for renewed effort is a metabolic priority.

Before training

With regard to carbohydrates during the pre-workout phase, the type and intensity of the training are determining factors. In case of high-intensity or strength training, carbohydrates are always the predominant source of energy so they can be ingested before the start of the session. The "burning" of fat essentially occurs when the workout is at an end. Carbs will actually have a limited effect on fatty acid oxidation, since the adrenaline and noradrenaline that are produced during the effort inhibit the secretion of insulin by the pancreas. In other words, the low insulin levels make it possible for fat to be used as long as the oxygen levels allow this, which does not happen if the intensity is high. I would consider the energy-yielding effect to be something positive in any context to keep the intensity elevated, although a lot still depends on the individual characteristics of each person. There is no one rule that can be applied to everyone. Insulin-resistant people who have less metabolic flexibility could benefit from restraining their carb intake.

Of course, there is more to a day than just training, and a lot of questions address carbohydrate intake in the morning and evening. The truth is that no formula works for everyone, and people can have varying degrees of tolerance. Besides, training time is usually simply the best time for taking carbs, or for taking them in higher quantities. In cases of people who have trouble losing weight however, breakfast can be a better time for carbohydrate intake, although here the quantities are best limited to 30-50 g. Such an amount will make it possible to replenish the liver glycogen spent during the night, and prevent peripheral blood glucose peaks at a time when the muscle is not particularly sensitive to the effects of insulin or influenced by any effort.

Carbs at night

As for dinner, there is no scientific evidence that recommends total carbohydrate intake restriction, although late meals may lead to limited fatty acid oxidation on the next day as well as during the night. There can even be benefits associated to the moderate intake of medium GI carbs roughly 2-3 hours before going to sleep, more specifically in terms of better sleep quality and appetite because of higher serotonin and melatonin levels. And if there is training done at the end of the day, which happens all too often, it can also be a way to reduce cortisol levels and replenish depleted muscle glycogen.

If losing weight and fat mass is the goal, the most important factor by far is the energy balance. Optimizing carbohydrate intake can possibly accelerate weight loss and improve training results, yet it should not be considered a weight loss strategy in itself. The peri-workout timeframe can be the ideal time to consume them, post-workout in particular, but depending on the individual and on the established goals, carbohydrates can play a key role in any weight loss diet.

Sérgio Veloso


Sérgio Veloso has a degree in Cellular Biology and a postgraduate course in Clinical Nutrition, having lectured, in recent years, several training activities on Sports and Functional Nutrition. He's also a consultant for the Fitness and Sports Supplements Industry, and a speaker at several national and international conferences.


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