Beach season is almost here. 

For those looking to lose pounds, Bob Harper, who gained fame as a trainer on NBC's "The Biggest Loser," appeared on the TODAY Show on Monday to promote his new book called "Jumpstart to Skinny."

Harper became a certified fitness instructor after college, but does not hold degree in nutrition. 

The fitness guru claims that his low-calorie diet plan will help adherers shed up to 20 pounds in just three weeks. 

On the extreme regimen, women are limited to just 800 calories per day, while men get a generous 1200. 

Harper says to drink 16 oz of water before every single meal, which makes you feel full. Previous studies have suggested that drinking water 20 to 30 minutes before a meal causes people to eat fewer calories later on, perhaps because they are not confusing hunger with thirst. 

Staying hydrated also means your body is not holding onto liquids since the water is constantly being replenished, Harper explained. 

You cannot eat complex carbohydrates, like grains and breads, after breakfast, or drink booze.

But you can eat as many vegetables as you want. 

"You're never going to get fat eating broccoli," Harper assured TODAY's Savannah Guthrie.

Watch the full clip below:
