Does Mass Gainer Make You Tired & Sleepy?

January 9, 2024 |

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In this article, I will discuss if mass gainers can make you tired and sleepy and what could be the possible underlying reasons.

The simple answer is Yes; you can have an energy slump after taking a mass gainer shake and end up yawning all day.

So, keep reading to find the reason why your high-calorie drink makes you feel exhausted and my tips on how you can avoid this issue when trying to bulk up with mass gainers;

Why does mass gainer make you tired? (WHY)

tired bodybuilder workout

Gainers are packed with energy-rich carbohydrates, proteins, and fats. These macronutrients significantly affect the sleep-wake cycle, secretion of sleep-causing hormones, and neural circuits.

As a result, your natural circadian rhythm (the system that induces sleep at night and wakefulness during the day) can be affected, eventually making you tired and inactive in the daytime.

Let’s dive into the details of how it all happens:

High Glycemic Carbs

The carb content is the primary reason for the fatigue-causing effect of your mass gainer, as some carbohydrates activate sleep-inducing hormones in the body.

That is why it is a common observation that you feel groggy after taking a large meal. However, in-depth studies have proven that not all carbohydrates induce the same effect. Instead, the sleep-inducing aptitude is higher for high glycemic carbs.

These molecules quickly convert into simpler forms inside the human body, causing a sudden increase in blood sugar levels.

Now, if you check the nutritional labels of the most popular mass gainers, you will likely find high glycemic carbs listed over there. The most common of these high GI molecules is maltodextrin.

Consequently, people who take a gainer shake feel a sudden boost in energy as maltodextrin and other high GI carbs spike up their glucose levels, but after some time, the sleep-inducing effects start dominating, and they feel tired.

If you take mass gainers for breakfast and want to minimize this effect, you should take a supplement packed with low-glycemic carbs.


High protein intake is also responsible for making you sleepy, and this effect is caused by a high proportion of a single amino acid named tryptophan.

However, tryptophan does not induce sleep by itself.

Instead, it acts as a precursor for serotonin hormone, which in turn causes the pituitary gland to secrete melatonin (the actual sleep-inducing hormone).

Micronutrients mass gainers

Mass gainers include a bunch of micronutrients that may enhance the protein synthesis, exercise performance, or absorptive efficiency of mass gainers.

Of these vitamins and minerals, vitamin B molecules (B3, B6, B12), iron, zinc, and selenium shorten sleep onset time (in other words, they make you more sleepy) because they act as cofactors in melatonin production.

Above mentioned factors are safe and beneficial because they improve sleep quality. But mass gainers also include ingredients that negatively impact the sleep cycle, energy, and attentiveness, causing drowsiness and exhaustion as listed next;

Saturated fats in mass gainers

Yes, like the other two macronutrients, fats’ proportion of the gainers also contributes to the fatigue and sleepiness you feel after consuming them.

However, unlike tryptophan or carbs, it does not have the natural sleep-enhancing effect and is an unhealthy consequence caused by saturated fats added to the supplement.

Saturated fats like medium chain triglycerides (MCTs) are known to decrease sleep quality. When deprived of quality sleep, you ultimately feel drained and groggy the next day.

Hence, choosing a gainer in which saturated fatty acids are very low is better to enjoy the benefit of MCTs and also escape the negative effect on sleep.

Artificial sweeteners in mass gainers

Mass gainer fatigue can also be a side effect of artificial flavors and sweeteners added to make them palatable.

Headaches, nausea, and insomnia are well-known adverse outcomes of artificial sweeteners.

Plus, NIH review confirms that these molecules interact with neural machinery and inhibit the production and release of many neurosecretions, including serotonin.

As a result, the melatonin secretion is reduced, causing insomnia (which ultimately leads to persistent fatigue), and neurophysiological activity is lessened, causing tiredness.

Weight gain

Another cause of mass gainers making you tired can be the weight you are gaining through it.

A surprising fact that has bubbled up through many studies is the connection of body weight with sleep. Thus, people having higher weights find it challenging to stay vigilant and energized for longer times compared to skinny individuals.

A study on the effect of weight gain on sleeping patterns inferred that when lab animals were fed a calorie-rich diet and gained a lot of weight, their wakefulness rates decreased.

On the other side, they were less sleepy when they lost weight.

The negative aspect is that this weight increase is primarily due to the fat mass (unless you pair it with regular exercise and turn it into a lean muscle).

Feeling sleepy after taking mass gainer? (REASON)

tired and sleepy man

As discussed above, mass gainers’ high nutrient content is the main reason it makes you feel tired and sleepy.

Suppose you have tried gainers from different brands and noticed that some of them make you dizzier than others. In this case, having a closer look at their nutritional labels can solve the mystery for you.

  • If the gainer contains maltodextrin, it will make you sleepy because maltodextrin has a high glycemic index.

Clinical trials confirm that sleep latency decreases when people consume high GI carbs close to bedtime. The participant who ate high glycemic diets took approximately 9 minutes to fall asleep, while others (who had low glycemic meals) needed 17 minutes.

  • Higher the whey protein content of your mass gainer, the more sleepy you would feel after taking it.
  • On the other side, if your mass gainer contains caffeine, it will increase your alertness but also interfere with your sleep if you take the shake at night.

Likewise, if your supplement contains a bulk of saturated fats, sleep quality may reduce. As a result, you will feel more exhausted the next day.

In a nutshell, if you want to gain weight healthily without disturbing your sleep cycle or feeling completely exhausted, you should look for a mass gainer supplement that does not contain maltodextrin or caffeine and has a small number of saturated fats only.

Is it good to drink Mass gainer before bed?

In short, yes, taking mass gainers right before bed is a good option.

However, the benefits and side effects of this timing can vary depending upon the formulation of your specific gainer.

Feel free to check out my post here to get complete information about the impact of timing on mass gainer results. 

Below, I have listed some science-backed facts on why taking mas gainers before bed can be a smart choice;

Increases muscle protein synthesis

High protein content, especially milk proteins (whey and casein), is beneficial for muscle growth when taken at night.

Research shows that taking protein supplements before bed can increase protein synthesis in muscular tissues and improve metabolic rates, leading to bulkier muscles.

In this observation, ISSN (International Society of Sports Nutrition) also recommends casein protein before sleeping.

Boost muscle strength

Similarly, pre-sleep protein ingestion improves the adaptive response of muscles, making them stronger and more resistant to injuries.

The journal of nutrition 2015 states that resistance training is more effective when athletes take enough dietary proteins besides working out.

Plus, consuming proteins before sleep is an effective strategy for enhancing muscle mass and strength.

Improves sleep quality

A good mass gainer can help you sleep better with its sleep-inducing ingredients like melatonin precursors (tryptophan), serotonin influencers (high GI carbs), and cofactors (Vitamin B, folate, zinc, etc.).

However, some care is needed because if your gainer contains a lot of caffeine, saturated fats, and artificial flavoring, you may end up with insomnia.

Why does serious mass make me sleepy?

Serious mass is one of the most calorie-rich products available out there, and I often hear complaints of tiredness and sloppiness from users.

If you, too, are also curious about it, the following are its ingredients that can be the potential cause of sleepiness;

  • It includes a lot of maltodextrins, which essentially make up the lion’s share of its calorie count. But its high glycemic index would also induce sleepiness.
  • It contains a bulk of saturated fats that lowers sleep quality, and you will be jaded and sleepy when deprived of sleep over time.
  • A lot of sleep-enhancing micronutrients are added to it like Niacin, vitamin B6 (5 mg), B12 (10 mcg), magnesium (140mg), folate (400 mcg), Selenium (70 mcg), and zinc (15 mg).


Mass gainers are energy-rich supplements used primarily for creating an energy surplus in the body. However, a conflicting complaint that often comes from users is that mass gainers make them sleepy and tired.

By looking at the scientific studies, I can say that this effect may be a positive consequence or a possible side effect depending upon the formulation of each product and the time you consume it.

Sleepiness induced by high protein content and micronutrients like vitamins and minerals is beneficial.

On the other side, saturated fats, excessive fat mass, and artificial sweeteners decrease sleep quality, causing constant fatigue.

And the sleep-induced effects of high GI carbs are fine at a low rate but become unhealthy if you take too much of them through your supplement.

Therefore, I would highly recommend you select a mass gainer based on how much you plan to work out and when – Timing is the key.

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