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Weight Gain Pills: Types, Efficacy, and Safety

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Science has come a long way — there is a pill for just about everything.

Heck, there are even pills marketed or intended to help you gain weight.

However, you may wonder whether these pills are effective or safe.

This article explains everything you need to know about weight gain pills and whether they are effective or safe for gaining weight.

weight gain pills

Types of weight gain pills

Weight gain pills fall into two categories — dietary supplements (over-the-counter) and prescriptions.

However, it’s important to understand that weight gain pills don’t directly help you gain weight.

Instead, they usually increase your appetite, allowing you to eat more calories, which over time, leads to weight gain.

Here’s what you need to know about weight gain pills, available as either a dietary supplement or prescription.

Dietary supplements

Dietary supplements don’t require a prescription — you can purchase them over the counter.

Several products claim to stimulate your appetite and promote weight gain.

They often contain a blend of herbs like maca root, ginger, and echinacea, among others.

While not marketed for weight gain, other dietary supplements like zinc, iron, and fish oil may restore appetite in some people, making it easier for them to eat more calories and gain weight.


Prescription appetite stimulants must be prescribed by a medical doctor or advanced practitioner like a physician assistant.

However, many of these drugs aren’t intended for weight gain, but they are commonly prescribed off-label for weight gain since they tend to increase appetite as a side effect.

Common prescription drugs prescribed to increase appetite and promote weight gain include:

  • Megestrol acetate (Megace). This drug is a synthetic version of the human hormone progesterone. It’s commonly prescribed for patients with advanced cancer and AIDS to increase appetite and promote weight gain.
  • Oxandrolone (Oxandrin). Oxandrolone is an anabolic steroid that prevents muscle loss and increases muscle mass.
  • Dronabinol (Marinol). This is a synthetic form of cannabis commonly prescribed to patients with AIDS-related weight loss and to treat nausea and vomiting caused by cancer treatment.
  • Mirtazapine (Remeron). Mirtazapine is an antidepressant used primarily for the treatment of depression but is commonly prescribed to increase appetite and promote weight gain.
  • Cyproheptadine (Periactin). This is an antihistamine used to relieve allergy symptoms but tends to increase appetite as a side effect.


Weight gain pills usually work by increasing your appetite. You can purchase weight gain pills over the counter as a dietary supplement. Alternatively, your doctor may prescribe appetite-stimulant drugs.

Are weight gain pills effective?

The evidence remains mixed as to whether weight gain pills are effective.

There is some research to support zinc, iron, and thiamine (vitamin B1) supplementation for weight gain, but only in people who are deficient in them (1, 2, 3).

Other studies have demonstrated that fish oil increases some peoples’ desire the eat while others have found certain essential oils like cinnamon bark, clove, and fennel useful for stimulating appetite (4, 5).

However, there is little to no evidence to support the efficacy of dietary supplements marketed for weight gain.

There is more evidence to support prescription weight gain pills but only because drug manufacturers must conduct clinical research trials before they can bring the drug to market.

And even then, the evidence of their efficacy for weight gain remains mixed.

This is primarily because studies differ in sample size, patient demographics, and characteristics, as well as appetite stimulant treatment, duration, and dose.

For each study that supports the effectiveness of prescription weight gain pills, there is another study that shows no benefit to them.

Therefore, it’s best to talk with your doctor to discuss your options if you believe a prescription appetite pill will work best for you.


There is limited evidence to support the effectiveness of weight gain pills. This is due to a lack of research on dietary supplements and differences in study designs for weight gain prescription drugs.

Are weight gain pills safe?

Just as their effectiveness varies so too does their safety.

Dietary supplements that contain single ingredients like iron and zinc are usually safe but then can cause harm when taken in excess and for too long.

Fish oil is generally safe to supplement long-term, just make sure to choose a quality brand like Wiley’s Finest.

Essential oils are also likely safe, assuming you use them for aromatherapy and don’t ingest them.

There is a greater concern for weight gain supplements that contain various herbs.

This is because these supplements often lack quality control, meaning the herbs could be contaminated or replaced with different plant parts that are less expensive.

As such, you should look for products that have been third-party tested by organizations like NSF or USP.

Like dietary supplements, weight gain prescription drugs can also have harmful or unpleasant side effects.

The most commonly reported adverse effect of prescription weight gain drugs includes (6):

  • Megestrol acetate (Megace): edema or fluid retention, constipation, dry mouth, abdominal pain
  • Oxandrolone (Oxandrin): harmful effects on the liver
  • Dronabinol (Marinol): dizziness, nausea, drowsiness, and euphoria
  • Mirtazapine (Remeron): dry mouth, constipation, drowsiness, and dizziness
  • Cyproheptadine (Periactin): irritability, nausea, and dizziness

The American Geriatrics Society recommends caution with the use of some of these appetite-stimulating drugs and advises against the use of others due to their ineffectiveness and high risk of adverse side effects in older adults (7).


Some weight gain pills like fish oil are generally well-tolerated while others — namely prescription drugs — have been associated with adverse effects like dry mouth, constipation, and dizziness, among other effects.

Tips to help you gain weight

Weight gain pills have their place, but there are other — likely more effective — things you can do to gain weight, even if you have a fast metabolism.

Eat smaller, more frequent meals

Eating smaller, more frequent meals allows you to consume more calories throughout the day.

This makes it easier to eat in a calorie surplus so you can gain weight.

Aim to have at least three high-calorie meals separated by 2–3 high-calorie snacks.

Drink your calories

Drinking your calories as opposed to eating them tends to fill you up slower (8).

Thus, if you struggle with a poor appetite, drinking some or most of your calories can make it easier to gain weight.

Homemade shakes and smoothies are a great option since you can load them with calories and tailor them to your tastes.

If you need ideas, here are several homemade high-calorie shakes and smoothies to try.

Emphasize fats

Opting to get more of your calories from fat is an effective way to boost your calorie intake.

This is because fat provides more than double the calories of carbohydrates or protein per gram.

Healthy sources of fat include:

  • nuts and seeds
  • nut butters
  • avocado
  • whole eggs
  • olives
  • whole-fat milk and yogurt
  • oily fish like salmon or tuna
  • oils like olive or canola oil

Try other weight gain supplements

Whole food should always be the priority, but supplements like weight gainers, protein powders, and meal replacements are useful for gaining weight.

Weight gainers range from 500 calories per serving on the lower end and up to 2,000 on the higher end.

Protein powders are much lower in calories than weight gainers but there are some higher in calories than others, making them a good choice for weight gain.

Despite the name, meal replacements shouldn’t replace a meal but they are great to consume between your meals for extra calories.


Other ways in which you can increase your appetite and promote weight gain include eating smaller, more frequent meals, drinking your calories, and supplementing your diet.

The bottom line

Weight gain pills may be available over the counter as a dietary supplement or prescribed by a doctor.

Most don’t help you gain weight directly but they may help by increasing your appetite, making it easier to consume the calories you need to gain weight.

Because they vary in their effectiveness for weight gain as well as their safety, it’s best to speak with your doctor to determine the best option.

Eating smaller, more frequent meals, drinking your calories, emphasizing fats, and supplementing your diet are helpful ways to promote weight gain.

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