How Long Does It Take to Gain Weight?

Medically Reviewed on 7/11/2022
How Long Does It Take to Gain Weight
On average, increasing your calorie intake by 500-1000 calories a day for 6 months will help you gain about 15-25 pounds

How long it takes to gain weight varies from person to person and depends on as age, sex, activity level, and other factors. 

When it comes to putting on weight, it helps to first define your goals:

  • Muscle gain: Slowly increase your calorie intake, especially protein intake, and do resistance exercises
  • Fat gain: Rapidly increase your calorie intake

On average, increasing your calorie intake by 500-1000 calories a day for 6 months will help you gain about 15-25 pounds. Calories should come from nutrient-dense foods rich in protein and healthy fats.

What factors affect weight gain?

The rate at which you gain weight is affected by the following factors:

  • Calorie intake (how many calories you consume in excess of the amount needed to maintain your current weight)
  • Genetic factors (genetic factors that contribute to your size, build, and metabolism)
  • Daily activity level
  • Eating habits
  • Age (your metabolism tends to slow down as you get older)
  • Hormone levels

6 tips for healthy weight gain

Set goals: Determine your weight gain goals, such as whether you want to gain muscle or fat. 

Calculate maintenance calories: Calculate your maintenance calories or the number of calories you require daily to maintain your current weight.

Start gradually: Gradually increase your calorie intake by about 300-500 calories per day (in the first week, you may experience a sudden weight gain of 4-5 pounds caused by the storage of water and glycogen)

Track your progress: Track your weight consistently and aim for a goal of  0.25%-0.5% of body weight gain per week.

Adjust as needed: Slowly adjust your calorie intake as you start to reach your goal weight.

Be patient: Keep in mind that weight gain is not linear, which means you may not keep gaining weight at the same rate throughout.

How to gain weight safely

Eating smaller, frequent meals: If you are underweight or have a small appetite, try to eat 5-6 smaller meals throughout the day instead of 2-3 larger meals.

Choose nutrient-dense foods: Healthy weight gain means you should be focusing on eating healthy, nutritious foods, such as whole grains, fruits, vegetables, lean protein, nuts, and seeds.

Focus on energy-dense foods: When you are trying to gain weight, opt for foods that are high in calories such as nut butters, plant oils, whole eggs, avocados, and full-fat dairy products

Drink smoothies and shakes: If you find it challenging to add to your calorie intake without feeling too full, try drinking your calories by making nutrient-dense smoothies and shakes.

Have an occasional treat: Even if you are trying to gain weight, be careful not to consume large amounts of sugar and saturated fats. Stick to nutritious and calorie-dense snacks, such as yogurt, granola bars, and bran muffins.

Do resistance: If muscle gain is your goal, include resistance training in your workout routine and make sure to target all muscle groups.


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Medically Reviewed on 7/11/2022
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Mayo Clinic. What's a good way to gain weight if you're underweight?

Leaf A, Antonio J. The Effects of Overfeeding on Body Composition: The Role of Macronutrient Composition - A Narrative Review. Int J Exerc Sci. 2017 Dec 1;10(8):1275-1296.

American Academy of Family Physicians. Healthy Ways to Gain Weight If You’re Underweight.