How to Gain Weight Fast (and Safely), According to Science

Weight loss is a popular pursuit, particularly at the start of the new year. But your health & fitness goals may not center around reducing the number on the scale. If you’re trying to gain weight fast — whether for sports or a desire to bulk up into a new shirt size — you need to know how to do so safely and effectively. 

While they might help, it’s not all about the mass gainer supplements. Here’s everything you need to know about science-based weight gain and how to properly move the needle. 

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Editor’s Note: The content on BarBend is meant to be informative in nature, but it should not be taken as medical advice. When starting a new training regimen and/or diet, it is always a good idea to consult with a trusted medical professional. We are not a medical resource. The opinions and articles on this site are not intended for use as diagnosis, prevention, and/or treatment of health problems. They are not substitutes for consulting a qualified medical professional.

Before You Continue

Weight management is a complicated, sensitive topic. While dedicated, rapid weight gain may not be as commonly sought out as weight loss, it merits just as much care and sensitivity. 

Studies show that chronic, dramatic overfeeding is correlated with negative health effects such as depression, disordered sleep, and more. (1)(2)(3) Significant, rapid fluctuations in body weight may put your health at risk and can predispose you to disordered eating behaviors. Consult with your physician or a qualified dietitian if you need personalized weight management care

How Weight Gain Happens

Weight change (whether gaining or losing) is a bit like an iceberg. On the surface, things are simple: If you eat more calories than you burn, you’ll gain weight, and the same is true for consuming fewer calories in an attempt to lose weight.

This mechanism, known as energy balance, is the principal factor driving weight change for just about everybody. However, under the surface lie a variety of sociological, psychological, and environmental factors that influence both your energy balance and the behaviors that regulate your eating habits. 

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[Read More: How to Bulk: The Ultimate Guide to Gaining Size]

So, barring certain medical conditions, if you find yourself gaining weight (or want to put on weight quickly), it’s because you’re in a net positive energy balance, period. But those circumstantial factors can affect how easy it is for you to find yourself in a calorie surplus in the first place.

For some, a busy lifestyle, familial obligations, or a hectic work schedule leads to unintentional weight gain. But what if those same circumstances make it difficult to get adequate nutrition? You need a practical, proactive approach to weight gain.

How to Gain Weight Fast

In the simplest terms, the formula for weight gain boils down to “eat more, move less.” If you’re adding strength training into the mix (and you should be), a portion of that weight gain will come from new muscle alongside body fat, water retention, glycogen, and so on. (4

[Read More: How to Gain Muscle — A Guide to Eating for Mass]

Here’s a step-by-step breakdown of the factors that contribute to gaining weight quickly, in order of importance: 

Eat More Calories

There’s no getting around it — if you want to gain weight, you need to consume more energy than you burn. To gain weight quickly, you’ll need to identify your caloric maintenance needs and then ingest a certain number of calories above that each and every day.

Calorie Calculator





Activity Level

BMR estimation formula


Your daily calorie needs: Calories Per Day

Daily calorie needs based on goal

Calories Per Day


Fat Loss

Extreme Fat Loss

Exercise: 15-30 minutes of elevated heart rate activity.
Intense exercise: 45-120 minutes of elevated heart rate activity.
Very intense exercise: 2+ hours of elevated heart rate activity.

[Read More: 5 Great Bulking Foods for Digestion, Intra-Workout, and More]

A 500-calorie excess, or surplus, should net you about an extra pound on the scale every week (since a pound of body fat equals 3,500 calories). If you’re performing strength training workouts, a portion of that extra weight should come from lean muscle mass instead of fat alone. 

Eat More Frequently

If you’re finding it difficult to increase your calorie consumption in order to gain weight, one of the best things you can do is increase the frequency of your eating. Adding two micro-meals or snacks between breakfast, lunch, and dinner can help you pack in some extra calories quickly, and smaller meals aren’t likely to make you feel too full to eat at all. 

Drink Your Calories

If you need to pack in some extra calories but can’t stomach another forkful of chicken and rice, turning toward liquid options may be your best bet. Calorie-dense beverages such as whole milk or meal replacement shakes can be ingested much more quickly than solid food and still provide heaps of nutrition in the process.

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Some studies have shown that liquid-based caloric intake leads to more substantial acute weight gain than solid food exclusively, but these results haven’t been measured over the long term. (5)(6

Reduce Your NEAT

Your body burns calories constantly, from the moment you wake until you rest your head on your pillow at night (and even while you’re sleeping). The energy you burn throughout the day, outside of dedicated exercise, is called NEAT: Non-exercise activity thermogenesis.

The higher your NEAT value is, the harder it’ll be to gain weight. (7) You can take small steps to reduce your NEAT (and thus lower your caloric maintenance level) by parking closer to the entrances of stores, sitting rather than standing when possible, and so on.

Just be sure to not take this to the extreme — there is a long list of health benefits related to maintaining a high level of general physical activity, and you shouldn’t neglect these things in an effort to put on a few extra pounds. 

Try Cold Water Immersion

If you find it difficult to gain weight because you lack for appetite, taking a dip in some icy waters might help get your stomach rumbling. Some studies have shown that cold water immersion (CWI) significantly stimulates appetite — as long as the water you immerse yourself in is roughly 20 degrees Celsius. (8)

Less Water, More Sodium

Your water consumption habits strongly influence your body weight on a day-to-day basis. The relationship between water intake and your weight, though, might surprise you. Generally speaking, the more water you consume, the less your body will feel the need to hold onto.

“Water loading” is a common practice for athletes who need to drop their scale weight quickly ahead of competitions. Conversely, drinking less water can help you retain more fluid and increase your scale weight accordingly. Upping your sodium intake can help as well since sodium causes further water retention. 

[Read More: The Surprising Benefits of Salt for Strength Athletes]

One study showed that 1.5 extra liters of water ingested per day was correlated with acute weight loss. (9)  Reducing how much water you drink may help you gain temporary scale weight, but understand that this isn’t a sustainable approach to putting on weight long-term.

Best Foods for Gaining Weight

To gain weight quickly, you don’t need to eat more food — you must consume more calories. Calorically-dense foods will provide the energy surplus you need to make gains on the scale without requiring you to shovel down extra-large portions at every meal. 

More specifically, you can make your weight gain journey easier by opting for high-sugar, high-fat food sources, which are more palatable and tempting (10) (just remember to not skimp out on your vitamins, minerals, and other micronutrients!) 

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[Read More: How to Count Macros for Weight Loss, Muscle Gain, and Maintenance]

Here are a few solid options. Note that these nutritional values are general estimates and may vary somewhat between products and brands: 

1. Nuts & Seeds

Nuts and seeds are a great option for putting down extra calories by the handful. Most foods in the nut family are extremely high in healthy fats (and equally calorically-dense). For example, a one-ounce serving of plain almonds contains roughly 170 calories.

2. Fatty Meat & Fish

If you don’t practice vegetarianism or follow a vegan diet, you should be eating meat to both hit your protein goals and put on weight. Go for fatty options like ground beef here. A 3-ounce serving of 85% ground beef holds 220 calories and comes with 24 grams of protein as well. 

3. Whole Milk

Whole milk is one of the most cost-effective, calorie-dense beverages you can buy. In addition to providing ample amounts of micronutrients like calcium and vitamin D, an 8-ounce serving of whole milk also contains 150 calories and 8 grams of protein

4. Weight Gainers

Weight gainers are nutritional supplements designed to, well, help you gain weight. Gainer powders come packed to the brim with lots of calories and carbohydrates to fuel high-volume weight lifting workouts.

[Read More: The Real Mass Gainer Pros and Cons, According to an RD and a Biochemist]

Nutritional contents vary significantly between brands, with some mass gainers offering in excess of 1,000 calories per serving.

5. Granola 

You can replace your morning cereal with granola and increase your caloric intake significantly in the process. For instance, one cup of granola can contain around 520 calories while also providing heaps of dietary fiber and other valuable micronutrients. 

6. Oils, Sauces, & Condiments

Dressing up your food can both make your meals tastier and increase the rate at which you gain weight. Certain condiments are extremely dense in calories. For example, just one tablespoon of cooking oil contains 120 calories (and 14 grams of fat). 

A two-tablespoon serving of full-fat ranch dressing has about 130 calories depending on the brand. Cooking with oils and putting condiments on your food is a great way to sneak extra calories into your meal without making you feel overly full. 

Your Takeaways

Rapid, intentional weight gain isn’t as popular as weight loss, but should be approached with as much dutiful attention and care if you want to gain weight safely. 

Gaining weight on the scale will mostly involve being in a calorie surplus, wherein your body consumes more energy than it burns.

Gaining weight on the scale isn’t necessarily the same as gaining “real” body weight.

Your “scale weight” is a result of your body’s physical weight, plus the amount of water you retain and the undigested food in your belly. 

Gaining weight quickly is best achieved by increasing the amount of calories you consume and reducing certain aspects of your physical activity.

Eating high-calorie foods, limiting unintentional exercise, and adjusting your sodium and water intake can help you quickly increase the number you see on the scale.

Weight management is a complex and deeply personal process. Making significant changes to your body can predispose you to disordered eating habits. Consult with a physician if you’re worried about managing your eating behaviors or body weight. 


Luppino, F. S., de Wit, L. M., Bouvy, P. F., Stijnen, T., Cuijpers, P., Penninx, B. W., & Zitman, F. G. (2010). Overweight, obesity, and depression: a systematic review and meta-analysis of longitudinal studies. Archives of general psychiatry, 67(3), 220–229. 

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Grigg, M. J., Thake, C. D., Allgrove, J. E., King, J. A., Thackray, A. E., Stensel, D. J., Owen, A., & Broom, D. R. (2023). Influence of water-based exercise on energy intake, appetite, and appetite-related hormones in adults: A systematic review and meta-analysis. Appetite, 180, 106375. 

Vij VA, Joshi AS. Effect of excessive water intake on body weight, body mass index, body fat, and appetite of overweight female participants. J Nat Sci Biol Med. 2014 Jul;5(2):340-4. doi: 10.4103/0976-9668.136180. PMID: 25097411; PMCID: PMC4121911.

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