Gaining 10 Pounds With A Fast Metabolism (for skinny guys)

Gaining 10 pounds with a high metabolism.

As a “Hard-gainer” myself, I know how frustrating it can be to put on weight. The issue is further complicated when you have a low appetite and a raging metabolic furnace. But fear not. I’ll explain why gaining 10 pounds is possible, even with a fast metabolism!

Generally speaking, it is possible to gain 10lbs of body weight despite having a fast metabolism. Doing so requires an individual to ensure a caloric surplus is consistently consumed. 20% surplus calories are recommended to “dirty bulk” and gain weight fast.

This post explains how to put on that coveted 10lbs and provides tips on how to beat your fast metabolism.

I gained 10 pounds with a fast metabolism.
I used to be a skinny guy with a fast metabolism but I was able to gain 10lbs of bodyweight in 2 months!

Key Takeaways

  • Gaining 10 pounds is possible for most people regardless of how fast their metabolism is.
  • It is recommended to go on a dirty bulk (requires you to consume a 20% calorie surplus every day).
  • Use my 9 tips to ensure you eat enough food to gain weight fast.
  • 35,000 total surplus calories are required to gain 10lbs.

How Your Body Gains Weight

How To Gain Weight As A Skinny Hardgainer

Weight gain is a simple process- you need to eat more calories than you burn. This is called being in a “caloric surplus”. It’s essential for bulking up as a skinny person.

The excess energy consumed during a bulking phase is then used by the body to store fat and build muscle.

As a result, you gain weight. And this mechanism is the same for everybody.

However, being a skinny person with a high metabolic rate, you need to ensure that you eat enough food to keep yourself in a surplus state.

Why It’s Hard To Gain Weight With A Fast Metabolism

Weight gain requires you to be in an energy-surplus.

But having a fast metabolism means you burn more energy even at rest. And this makes it more difficult for your body to enter a surplus state.

The solution is to determine exactly how many cal you need to eat to be in a surplus and eat enough food to get those calories (see next).

3 Steps To Gain 10 Pounds On A Fast Metabolism

How to gain 10 pounds with a fast metabolism.

Following the below three steps will help you succeed in gaining 10 pounds, regardless of how high your metabolism is.

1) Find Maintenance Calories

Your maintenance calories are what your body burns every day to sustain its current weight

This is a crucial step.


Because determining your maintenance calories lets you know the minimum number of calories required to gain weight.

You can find your maintenance calories using an online calculator. The TDEE calculator gives you a ready-to-use number that also factors in your basal metabolic rate (BMR).

2) Identity Dirty Bulking Calories

Now you can add 20% to your maintenance calories to go on a dirty bulk.

For example- if you burn 2200 maintenance calories every day, then a 20% surplus means you should be eating ~2640 total daily calories to gain weight. That’s a 440 cal surplus per day.

Generally speaking, most people with a high metabolism need around ~500 surplus calories to bulk up at a fast rate.

Additionally, 35,000 surplus calories are required to gain 10lbs of body weight.

Thus, eating in a daily 440 cal surplus will take you ~80 days to put on 10lbs (2-3 months).

3) Consume Your Target Calories For A Dirty Bulk

Now you need to actually plan your meals such that you satisfy your daily dirty bulking targets.

Successfully reaching your target calories is the best way to ensure success in gaining 10 pounds on a high metabolism.

The 9 tips below can help skinny people with low appetites to eat more food.

9 Tips To Quickly Gain Weight On A Fast Metabolism

Skinny people often have a low appetite. This is detrimental for bulking up since weight gain is predicated on eating more food.

Follow these 9 tips to increase your calorie intake, reach nutrition targets, and succeed in gaining 10 pounds with a fast metabolism.

1) Identity The Reason You Aren’t Gaining Weight

Many reasons exist why people stay skinny. But speaking from personal experience, the most common reason is simply consuming an inadequate amount of food.

In fact, it’s common for skinny people to overestimate their total calorie intake and mistake this as having a high metabolism.

I could not gain weight because I was not eating enough food.
I thought my fast metabolism was the reason why I couldn’t gain weight but it was actually because I wasn’t eating enough food.

In reality, most skinny dudes simply don’t gain weight because they’re undereating.

I recommend calorie counting a typical day of eating. How does the number compare to your maintenance calories?

If it’s about equal or significantly lower, then you know this is a big culprit as to why you aren’t gaining weight.

2) Slowly Add More Calories To Each Meal

This is an effective solution to combat a low appetite.

Don’t fall for the mistake of drastically increasing food intake overnight. This is a recipe for disaster. Not only will it make you extremely bloated, but it’s also very unhealthy.

Instead, bump up the calories by 100-200 each meal day by day.

By slowly increasing the volume of food in each meal, you ease your stomach into a dirty bulk.

3) Eat Slightly Smaller Portions But More Frequently

Most people eat 3 meals per day and sometimes even less.

This is not recommended when you are trying to bulk up.


Because it forces you to cram in as much food as possible in a limited number of meals.

The solution is to increase meal frequency. Instead of eating 3 meals per day, eat 4-5 instead. This means you need to eat less food per meal to reach your daily nutrition target.

Typical bulking diet for someone with a low appetite and fast metabolism.
A typical day of eating for me whilst bulking.

And this helps a lot with reducing the uncomfortable bloating that often comes with a bulk.

I recommend making one of these meals a pre-bed snack.

Most of your body’s repair and muscle regeneration processes happen during deep sleep. So it’s good to keep your body topped up with energy overnight to fuel weight gain.

4) Consume More Energy-Dense Foods

Energy-dense foods are typically high in fats and sugars. Examples include:

Foods To Gain Weight On A Fast MetabolismTypical Calories Per 100gTypical Protein Per 100g
Grains (pasta, oats, bread, rice)36012g
Peanut and almond butter60025g
Sweet fruits1000g
Fatty cuts of meat20020g+
Oily fish21020
Olive oil8800g
Nuts and seeds58021g
Cow’s milk (100ml)453g
Coconut milk2302g
Full-fat cream3802g
Whey protein powders15025g
Weight gainer powders100050g

They contain lots of calories for a very little volume. This can help skinny people reach their nutrition targets with minimal bloating, and succeed in gaining 10 pounds despite a low appetite or fast metabolism.

5) Blend And Liquidize Your Meals

This is a ninja hack for anyone with a low appetite.

Liquid meals are easier to consume and faster absorbing compared to solid meals. Simply blend ingredients into a shake.

By combining energy-dense ingredients, it’s quick and easy to make a homemade weight gainer shake that packs in excess of 1000 calories.

A homemade weight gainer shake.
It may not look appetizing, but a simple shake packs a lot of calories!

These can be had at any time during the day. But I love consuming these for breakfast.


Breakfast is one of the most important main meals for gaining weight since your body is exiting from a fasted state.

It’s also a meal that many skinny beginners struggle to eat enough calories on.

A calorie-packed shake is a delicious and convenient way to consume a significant chunk of your calorie target at the start of the day.

6) Reduce Physical Activity

Excessive cardio and physically-demanding jobs will increase your daily energy expenditure.

And this makes it harder to be in a caloric surplus.

Try to cut back on the weekly hours you spend running, biking, etc. And try to reduce manual labor as much as you can.

If this isn’t possible, then you need to consider eating more food to replace the energy burned through your physical activities.

7) Do Not Rush A Bulk

A typical bulking phase lasts anywhere between 3-6 months or more.

There’s a reason for that.

A longer bulking duration is more sustainable because it allows you to go on a smaller calorie surplus. And the smaller the surplus the easier it is to maintain.

So give yourself ample time for bulk and do not rush it.

This sets you up for long-term success in gaining 10 pounds with a fast metabolism.

8) Consider Increasing Bulking Timeframe

I know it’s tempting to go on a bulking crash course to gain weight fast.

But trust me- these are unsustainable, unhealthy, and have a low chance of success.

It’s better to go on longer bulk with a higher chance of succeeding than it is to go on a short and extreme bulk with a low chance of succeeding.

9) Plan And Track Weight Gain Progress

For most people, gaining 10lbs usually takes 1-2 months (minimum).

During this time, it’s essential that you track and log your weight gain. This allows you to identify and troubleshoot any problems with slow rates of weight gain.

The last thing you want is to realize at the end of month 2 that you aren’t eating enough surplus calories to gain weight.

Good metrics to track include:

  • Weight gain. Take the weekly average across 7 days. You should be gaining at least 1lb per week if you’re dirty bulking correctly.
  • Calorie intake. Record how many calories you are eating per meal for every meal.
  • Protein intake. Record how many grams of protein you’re eating per meal. Protein is key for muscle gain.
  • Weight training progress. Keep track of the weight you are lifting on each exercise if you’re looking to build muscle. It should be getting heavier each week.
  • Progress photos. You should notice yourself getting noticeably bulkier within a month.

Reasons You Have A Fast Metabolism

Your basal metabolic rate (BMR) is affected by multiple factors that are within and outside your control:

  • Sex. Men generally have a higher metabolism than women.
  • Age. Young people generally have a faster metabolism than older people.
  • Muscle mass. The more muscle mass you currently have the higher your metabolism.
  • Physical activity. This increases the amount of energy expended and therefore increases your metabolism.
  • Cold temperatures. This causes your body to burn more energy to maintain your body temperature.

The last two factors are the only viable ways to control your metabolism.

Reduce physical activity and heat up the ambient room temperature.

This can reduce your metabolism and help you succeed in gaining 10 pounds.

Expected Timeframe To Gain 10 Pounds With A Fast Metabolism

The average person consumes between 500-1000 surplus cal on a dirty bulk.

If it takes 35,000 surplus calories to gain 10 pounds, then that’s 35-70 days required to reach your goal.

Thus, most people can gain 10 pounds in around 2 months. And that’s enough time to get significantly bulkier.

However, it’s essential that you consistently eat your surplus calories on a daily basis to combat the effects of your fast metabolism.

Can You Do It Faster?

It’s possible to bulk up by 10lbs in less than a month.

For example, you could theoretically gain 10lbs in just 7 days if you’re able to consume enough calories during that short timeframe.

However, this is considered to be an extremely fast rate of weight gain.

Not only is it unhealthy, but also very difficult to succeed in eating so much food.

Gaining 10 Pounds Of Muscle On A Fast Metabolism

Gaining muscle weight is much harder than gaining general body weight. To quickly build 10lbs of pure muscle at a high metabolic rate requires:

  • Intense weight training.
  • Calorie surplus.
  • High protein intake.

These 3 factors combined will help you drive muscle growth regardless of how fast your metabolism is.

Just make sure you account for the calories expended during training to make sure you remain in a surplus.


Gaining 10 pounds is possible despite having a fast metabolism.

However, it’s essential that you put yourself in a caloric surplus state.

This can be done by determining your maintenance calories, adding 20% to get your total daily target calories, and planning your meals to reach that target.

You’ll need to eat 35,000 surplus calories to gain 10lbs of body weight and this usually takes around 2 months.

You may also be interested in the downloadable Kalibre Blueprint PDF which details exactly how I gained 40lbs of lean muscle (it’s 100% free!). It details the exact exercises and nutrition (with printables) I used to go from skinny to ripped!


I'm Kal (B.S, M.S)- a health & fitness writer and owner of Kalibre Fitness. I love to nerd out on weight training and nutrition. My primary interests are in muscle hypertrophy mechanisms and strength development. You can connect with me in the "Contact Us" section below!

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