How to Gain Weight With a Fast Metabolism: Unlocking the Secret

You’ve probably come across people who eat a lot of junk food but don’t gain weight. Then there are those who strictly watch their diet but find it difficult to lose weight. That is where metabolism comes in. This is the article to read if you want to understand how a fast or slow metabolism impacts weight.


The Metabolic Phenomena: Thrifty vs. Spendthrift

The Science Behind Weight Gain and Metabolism

The Impact of Macronutrient – Unbalanced Diets

Metabolic Flexibility: The Key to Weight Management

Practical Strategies For Gaining Weight With a Fast Metabolism


The Metabolic Phenomena: Thrifty vs. Spendthrift

Understanding the metabolic spectrum from thrifty to spendthrift is very important. That’s because it helps in unraveling the mystery of being underweight despite adequate calorie intake.

Some people are genetically predisposed to having a “thrift” metabolism. This enables their bodies to store fat more efficiently for later use such as when fasting. Then some have a “spendthrift” metabolism. This allows them to churn through calories quickly instead of storing them as fat.

Keep in mind that some people are naturally underweight simply because of their genetics. Others are underweight because of a fast metabolism, which is an indication of a spendthrift metabolic response.

Our body’s energy expenditure response to fasting and overfeeding also helps to determine where we fall on the metabolic spectrum. Thrifty metabolisms lower energy expenditure during calorie restrictions. In contrast, spendthrift metabolisms increase energy expenditure during overfeeding as a way of trying to burn excess calories.

The recently discovered hormone called Fibroblast growth factor 21 (FGF21) plays a crucial role in these metabolic responses. This hormone is secreted during fasting to induce fatty acid release and suppress carbohydrate utilization. Some people may be predisposed to having higher levels of FGF21, which leads to a faster metabolism.

The Science Behind Weight Gain and Metabolism

Metabolism is a series of chemical reactions in our bodies that create and break down the energy necessary for life. This important biological process encompasses a series of intricate chemical reactions that sustain life.

It’s through the metabolic rate that food undergoes breakdown. This process results in the conversion of nutrients into energy, which is further used in various physiological activities such as generating heat.

While it’s important to understand the spectrum of metabolism, it’s equally crucial that we delve into the science that underpins weight gain. We need to understand how our bodies manage energy.

Being underweight is defined as having a body mass index that’s below 18.5. This is estimated to be less than the body mass required to sustain optimal health.

The principles of thermodynamics and human body energetics reveal that weight change boils down to energy balance. This refers to the relationship between energy intake and expenditure. Consuming more calories than your body can burn leads to weight gain while the opposite causes weight loss.

However, there’s considerable variability across the population in weight change in response to identical calorie surpluses or deficits. This highlights how metabolism impacts energy balance and the difficulty that some people face in gaining weight. 

The Impact of Macronutrient – Unbalanced Diets

Macronutrients are the things that we eat the most. They’re the major food categories from which we get most of our calories.

Balancing macronutrients can well be the source of what is said to be a balanced diet. A diet that’s largely imbalanced in macronutrients can cause overeating and appetite fluctuations.

If your body fails to get enough of the macronutrients, it will literally be starving on a nutritional level no matter the amount of calories you consume. This effect will make you hungry all the time, “forcing” you to eat so that your body gets what it needs.

Note that the kind of food we eat plays a role in how our bodies process and store energy. Eating donuts, for instance, and other foods may cause you to gain weight initially. But the problem is that it can also increase your risk of developing heart disease, diabetes, and cancer.

Studies have shown that low-protein feeding leads to a dramatic increase in fat storage. It also causes minimal change in energy expenditure. In contrast, overfeeding on proteins causes a significant rise in energy expenditure with less fat gain. This is related to the thermic effect of food, which is the energy needed for digestion, absorption, and disposal of ingested nutrients. Proteins have the highest thermic effect followed by carbohydrates and fat.

High dietary fat intake also promotes positive energy balance. Furthermore, it promotes weight gain by reducing satiety signals and stimulating passive overconsumption of calories.

Metabolic Flexibility: The Key to Weight Management

Our body’s metabolism benefits from our being flexible. Thus, instead of only having the ability to use carbohydrates or fat for energy, a flexible metabolism can switch between both with ease. That state is what we call metabolic flexibility.

Assuming that it has been a while since you last ate, your metabolism switches over to burning the fuel that’s in your body. This fuel can be fat or sugar, and the fuel-burning processes are referred to as fat oxidation and glucose oxidation. So, to manage different energy sources, we must consider our body’s adaptability and flexibility.

Note that if your body can’t alter how it uses different types of nutrients for fuel, meaning it has metabolic inflexibility, it will have difficulties adapting to using different fuels. Obese individuals, for instance, tend to preferentially burn carbs rather than fat. This metabolic inflexibility leads to weight gain, making weight loss more challenging.

Boosting fat oxidation rates appears crucial in combating daily positive energy balance. Even brief, post-meal bursts of fat-burning can minimize fat gain versus storing excess calories entirely as fat. 

Practical Strategies For Gaining Weight With a Fast Metabolism

Now that we’ve delved into the intricacies of metabolism and its impact on weight, how about exploring actionable strategies for those looking to gain weight healthily?

  1. Increase Caloric Intake

You’ll need to consume more calories than those that your body burns to gain weight. Scientists refer to this as a calorie surplus. You can calculate your daily caloric needs using an online calculator and increase your daily caloric intake by 500-1,000 calories. This will help you to gain weight.

  1. Eat More Frequently

To increase your caloric intake, it’s recommended that you eat smaller, frequent meals throughout the day. Consider having six meals a day with three main meals and three snacks. This will prevent hunger and keep your energy levels stable.  Be sure to include a protein source in each meal and snack such as eggs, fish, chicken, or yogurt. 

  1. Eat Nutrient-Dense Foods

It’s important that you choose nutrient-dense foods. These include whole grains, fruits, vegetables, lean protein, and healthy fats. These foods will provide your body with essential vitamins and minerals that are helpful for your overall health.

  1. Lift Weights

Strength training helps with muscle growth and weight gain. It also helps to build muscle mass, which can lead to weight gain. So, you should aim at lifting weights at least three times a week. Focus on compound exercises like squats, deadlifts, and bench presses.

  1. Get Enough Sleep

Sleep is important as it helps with muscle recovery and growth. Sleep for at least 8 hours a night to allow your body to recover and build muscles. Inadequate or lack of sleep can lead to decreased energy levels and reduced physical performance.

  1. Limit Cardio Exercises

Cardiovascular exercises are necessary for your overall well-being. The challenge is that they can be counterproductive if you’re trying to gain weight.

A lot of cardio burns off excess calories, which makes it difficult to gain weight. So, limit cardiovascular exercises to two or three times a week. Then, focus on strength training, which will help you to build muscle mass.

  1. Be Consistent

Consistency is important if you’re to gain weight. Stick to a consistent meal and workout plans, and be patient for the results. It can take several weeks or months to notice the results of your efforts.

So, have you been wondering about how to go about gaining weight with a fast metabolism? There you have it! It can be challenging, but the above strategies will help you push past the barrier and gain weight slowly and steadily.


Metabolic flexibility is proof that diets are not a one-size-fits-all strategy. There are benefits to phasing between different styles of eating, and doing so helps to support your overall well-being.

Remember to eat nutrient-rich, whole foods, drink enough water, manage stress, and exercise. This will help you to build a healthier lifestyle, balance your hormone levels, prevent diseases, and prolong longevity. 

Gaining weight when you have a high metabolism can be a challenge, but it’s not impossible.

Increase your caloric intake, focus on protein and healthy fats, and incorporate nutrient-dense foods. Don’t forget to lift weights, get enough sleep, limit cardiovascular exercises, and be consistent in everything you do.

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