How Many Calories Should I Eat to Gain Weight?

When gaining weight, sometimes you just want the certainty of hitting the right calorie intake and getting the results, wondering how many calories should you eat to gain weight. It can become complicated when we break it down into macros and then you have to worry about different priorities.

Today, we’re simplifying. We’re breaking down the basics of how much you should eat to drive a healthy weight gain. We’ll start off with ‘how many calories should I eat to gain weight’ for the average person and then what factors change your needs up or down.

By the end of the article, you should have a solid grasp on what you need to eat, why, and how to personalize beyond normal needs and goals!

How Calories Work for Weight Gain

Calories are your guiding light when it comes to dieting up or down. Whether you’re looking to gain or lose weight, they’re the number you watch to make sure you’re eating enough, but not too much, to drive your goals.

What is important is that it’s a unit of the energy in food – not the healthiness. Some foods and their calorie intake may be appropriate for your diet, but it’s about finding the space in your diet for these foods and their energy.

You have an energy requirement every day that your body uses to perform activities and background processes for recovery. These are the baseline for calorie intake, and then the amount you eat above or below this will drive weight gain or loss.

Understanding Calories

When we talk about calories today, we’re not talking about the macronutrients or food sources they comprise. It’s not the focus, but it’s quite important once you’ve figured out what you need to support the weight change you’re looking for.

Understanding what calories are and how they work is key. You just need to use foods and their individual calorie content and portions to chase goals.

When it comes to weight gain, that means eating more overall or eating more calorie-dense foods. Obviously, one of the options for weight gain is just to increase the portions of your food from a maintenance level and add 10-20% to each meal.

It is usually more complex in practice, so let’s get into how we use calories to enable weight gain.

Using Calorie Math to Gain Weight

The idea of calories is to estimate your normal needs – TDEE – and then go up from there to gain weight. When you eat more than you use, you’re going to gain weight. When that’s combined with regular exercise and smart macronutrients, you’re going to gain muscle mass, bone density, and other health benefits.

The average TDEE is around 2500 calories per day, when we average out between the normal woman and man. For these people, calorie intakes above 2500 are typically going to lead to weight gain.

When we look at weight gain in fat, the estimate is around 3500 calories per pound of fat. So, when you eat 3500 calories more than you use with no exercise influence, you’re typically gaining a pound of fat.

When you’re trying to gain muscle, it’s a bit more difficult. The process is not only slower and more limited in how fast you can push it, but it requires more calories. The average pound of muscle is estimated to take around 7000 calories over maintenance to build, combined with effective training stimulus.

The idea is that you split these demands across 1 week (for fat) and 2 weeks (for muscle) – which usually leaves us with a 500 calorie surplus. This is why the average recommendation for weight gain is a 500 calorie surplus per day, which can be increased or reduced.

This is important for most people because the amount of surplus also determines the amount of fat vs muscle gained in a pound of weight gain.

You’re likely to get some of both, no matter what, while macronutrient choices, exercise choices, and other recovery (like sleep and supplementation). Slower weight gain typically means better quality, where faster just means more fat accumulation.

Muscle Gain vs Fat Gain: What are You Gaining?

This is one of the important parts of the process of weight gain. For most people, weight gain that is richer in muscle mass is the goal.

This is the kind of weight gain that is most healthy and is most closely associated with performance improvements. In any sport, muscle mass gain is better for power and strength, so being more muscular is good.

However, if you’re using weight gain diets to overcome a severe underweight condition, you can go faster. You want to maintain healthy metabolic function but gaining a little extra fat may be part of the goal.

It’s always important to remember that when we talk about what is best, it’s for most people most of the time, and may not fit your situation.

TDEE: How Many Calories Do You Use in a Day?

TDEE is the place where calorie math all starts. This is a very vague estimation of your energy needs for all the processes and activities you’re going through in a day. It’s a baseline that we use to adjust diet and training to support goals.

Estimate is the important word here.

A lot of the criticism comes from the fact that it’s not a perfect science and that many people fall outside of the estimates and need to adjust on the fly. There are a number of factors like genetics, food sources, and other lifestyle factors involved in the actual, specific number of calories you use in a single day.

The idea is that – if you’re getting on the right side of your TDEE with enough frequency, you’re going to make the changes you want. From there, you can tweak your diet to drive results. Not gaining weight? Add more calories to your diet. Gaining too much too fast? Dial it back slightly.

It’s a starting point from which you get it right. It’s okay to not have everything perfect from the start.

How Many Calories Does the Average Person Need to Gain Weight?

If you’re a normally-sized person in the BMI ranges that are most common, we’re using you as an example. Let’s say you’re an 85kg man at 5’9 exercising 3 times a week (which is what ‘regular exercise’ looks like).

Your TDEE is probably 2500ish, so we start with that as a baseline of calories. If you’re looking for patient, sustainable weight gain that prioritizes muscle mass over fat gain, you’d typically aim for a 500-600 calorie surplus. That means 3100 per day, allowing for small variations.

The key is a weekly average of 3100 per day. It’s okay to vary up and down, if that’s what logistics and your food choices look like.

Individual Needs and Calorie Intake

What is interesting as a factor in changing these numbers is individual body composition and exercise output. These are the differences that make most of the difference between two men of equal height and weight (thus BMI).

The amount of muscle mass one man is carrying will determine his needs. More muscle produces more calorie-need to keep up this metabolically-expensive tissue. It also typically involves exercise output that is higher – also driving up calorie needs.

It’s not uncommon to see a high-fat, low-muscle individual who only needs around 2200 calories, while his more muscular and active counterpart may maintain at 3200. For these two men, their goal calories might be 2500 and 3500 respectively.

How your body size, weight, and composition change weight gain

This is also important when dealing with your own calorie goals: larger people are able to sustain larger surplus and deficits.

For example, a very large and muscular man with a 4000 calorie TDEE is going to be able to gain weight with an 800 calorie surplus without gaining as much fat. That’s because the weight gain proportional to his existing weight is just not as significant.

On the opposite end of the spectrum, a 50kg woman may have a less “pure” muscle weight gain even using 500 calories. She’s likely to gain more fat on this diet. If her existing baseline is around 2000 calories, this is a significant increase (25%) relative to the 800 calories for our large man (10%).

Try to keep the proportions in mind. It’s one of the reasons why percentages and multiples are often used. They apply more closely to everyone, which is why the 10-20% guideline is a good way of setting out your calorie intake goals.

Activity levels, exercise, and weight gain

Obviously, then we have to consider your activity levels, intensity, and goals.

The science is clear: more intense, high-volume training is more effective in making the most out of weight gain. It’s a process that improves hormonal health, protecting you from the worst effects of rogue weight gain, and making the most of your surplus calories.

When you consume more than you eat, exercise is the major determining factor in the fat vs muscle gain balance. Resistance training is the most effective form of muscle-gain training, along with bodyweight exercise and other strength-based methods.

Beyond that, the challenge that training poses and the amount of loading it places on the muscles is the key driving factor. In the simplest terms, the more you can do and recover from, the more muscle you can gain.

There is an upper limit to this, though. We call it ‘maximal recoverable volume’ and it’s the upper limit after which you stop producing results. After that point, you start causing breakdown and detraining as your body can’t recover and improve because it’s so busy trying to recover from the immense effort.

This is the sweet spot that we aim for in training, just below maximum recoverable, where intense results may continue to drive high-quality weight gain for 42-52 weeks. These results come from consistent, smart training multiplied by the dietary energy (calories) and nutrients that make positive change possible.

Frequently Asked Questions

How many calories do I need to gain weight?

An 85kg man exercising 2-3 times a week should eat anywhere between 2750 and 3500 calories to gain weight. This depends on activity levels, existing muscle mass, and other dietary needs.

You should use a TDEE calculator [LGR2] to figure out your rough needs – then add 250-750 calories. Bigger people need more, smaller people need fewer. It’s also an estimate, so make sure you adjust up or down based on your weight change.

How many calories to gain a pound?

That depends on the pound: 3,500 calories for a pound of fat or roughly 7,000 for a pound of muscle.

These are rough estimates, but a great place to start. They also break down to 500 calories below TDEE for a week for fat loss, or 500 calories above TDEE for 2 weeks to gain a pound of muscle. This is a great rule of thumb that has worked for athletes for decades.

How many calories do you use in a day?

That depends on your height, weight, muscle mass, and activity levels – among other things. You can use a TDEE calculator (mentioned above) to estimate your needs.

This is how most people structure a weight gain – or loss – diet.

Closing Remarks

The amount of calories you should eat to gain weight is deeply personal. You should start with the math of TDEE and a 10-20% increase to drive weight gain. However, it’s important to remember that it’s a starting point and not carved in stone. Your actual needs can diverge quite significantly from these numbers.

Be willing to experiment with the numbers and eat for the effects, not just the number. If you’re not gaining high-quality weight, then you may need to go up, and don’t worry about the number itself. A lot of calories for you may not be many for someone else, and vice versa.

Remember that calories are a tool for your goals and not something to chase by themselves. Weight gain balances speed and quality, where patience rewards you with more muscle, less fat, and better health.

Calories are a tool to take you from your current weight to your goal weight – or whatever metric you’re using. Today we’ve outlined how they do this, how you use them, and some of the considerations that determine how many calories you should eat to gain weight.

Start with TDEE, start with your goals, and be willing to change as time goes by. If it’s working, you’re in the right place. If it’s not, it’s easy to tweak the numbers!