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Just as it sounds, the gallon of milk a day (GOMAD) diet involves drinking one gallon of milk per day.

Proponents of the diet claim it quickly helps you gain weight, boost testosterone, and increase muscle strength.

However, you may wonder whether these claims are true and if drinking one gallon of milk per day is safe.

This article explains everything you need to know about the GOMAD diet and whether you should try it.

GOMAD diet

The GOMAD diet

The GOMAD diet involves drinking one gallon of milk per day in addition to your normal diet.

The diet is intended to help those who struggle to gain weight and want to build muscle.

There are no specifics about the type of milk you must drink as long as you drink one gallon each day.

Many people choose to drink whole milk since it provides more calories than 2% or skim milk.

One gallon (3.79 liters) of whole milk provides roughly (1):

  • 2,400 calories
  • 125 grams of fat
  • 128 grams of protein
  • 182 grams of carbohydrates

Milk is a great source of high-quality protein and has been shown to support muscle growth when consumed after a workout (2).

While there is no set guideline for how long to follow the GOMAD diet, most people follow it for several weeks to gain weight.

Effects on testosterone

Testosterone is the primary male sex hormone that plays an important role in muscle growth (3).

The GOMAD diet is said to boost testosterone, thereby increasing muscle and strength gains.

This is because milk — especially whole milk — provides a significant amount of saturated fat.

Some studies have linked meals high in saturated fat with temporary increases in testosterone (4, 5, 6).

However, this effect is unreliable, and other studies in men have shown that testosterone levels decrease after consuming a meal rich in saturated fats (7, 8, 9).

Therefore, it’s unlikely that drinking a gallon of milk would have a positive effect on your testosterone levels.

Even then, testosterone levels may not be a strong predictor of muscle growth.

Instead, research suggests that the number of androgen receptors your muscle contains may be more important for building muscle than your testosterone level (10).

In either case, drinking a gallon of milk per day provides a significant amount of saturated fat.

While saturated fat is not directly linked to heart disease, it has been linked to an increase in some heart disease risk factors like high cholesterol (11, 12, 13).

It can help you gain weight

Proponents of the GOMAD diet claim it’s an efficient way to help you gain weight quickly.

This is because it’s easier to drink an additional 2,400 calories per day from milk than it is to eat them.

Liquid calories like milk tend to have less of an impact on fullness than calories from solid food, and milk also contains no fiber, which can promote fullness.

Despite these attributes, drinking a gallon of milk per day is no easy task.

Drinking a gallon of milk per day on top of your normal diet may cause stomach distress like bloating, nausea, diarrhea, and potentially vomiting, especially around your workouts.

Because of these potential side effects, you may intentionally decrease or change what you normally consume, which could mean consuming less healthy and filling foods like fruits and vegetables.

Aside from these factors, trying to drink a gallon of milk per day can be highly inconvenient, depending on your lifestyle and daily routine.

Should you try it?

The GOMAD diet is an extreme but effective way to gain weight fast.

However, depending on how many calories you normally consume, adding 2,400 calories per day from milk can put you into a very large calorie surplus.

If you’re in a calorie surplus, you consume more calories than your body needs.

A calorie surplus is necessary to gain weight, but too large of a surplus can result in rapid fat gain.

Instead, a more modest calorie surplus of 300 — 600 calories per day in combination with weight training will limit fat gain and help maximize muscle gains (14, 15).

These extra calories should come from nutrient-dense, whole foods, such as fruits, vegetables, whole grains, dairy, meat, fish, poultry, nuts, seeds, and oils.

If you struggle to eat enough throughout the day, try making a high-calorie, high-protein shake using whole milk, frozen fruit, Greek yogurt, peanut butter, and Optimum Nutrition Whey Protein Powder.

The bottom line

The gallon of milk a day diet is popular among those who have trouble gaining weight and want to build muscle.

While the diet can help you gain weight quickly, it likely has no significant effect on testosterone levels and can come at the cost of stomach discomfort and unwanted fat gain.

Instead, consume 300 — 600 calories more per day than you normally consume in the form of nutrient-dense, whole foods.