As a general rule, athletes should eat “clean.” But what does that actually mean? Eating clean means eating natural, minimally-processed foods that are low in calories and rich in protein, fiber, vitamins, and minerals. These sorts of food give your body the nutrients it needs, are good for your digestive system, help you live longer, and keep systemic inflammation low.   

As a side benefit, a meal plan focused on those outcomes can also make portion control and fat loss easy.

However, high-level athletes and bodybuilders have another consideration: Unlike most people, they often need to make an effort to eat more calories, not fewer.  The trouble is, all of the usual arguments for eating clean still apply to them, and the imperative to eat more calories may at times seem like it conflicts with the need to eat clean.    

Related: 5 Ways to Put on 10 Pounds of Lean Muscle FAST

The vertical diet is one of many specific meal plans designed to solve this problem for athletes and bodybuilders. In short, it focuses on foods that are minimally processed and easily digested, but also relatively high in calories.  

Minimize Your Consumption of These Foods

There are certain foods that athletes should greatly minimize on the vertical diet, for one of two reasons. First, many of these foods are largely empty calories, devoid of useful nutrients.

Second, some foods contain anti-nutrients — chemicals that can inflame the lining of your gut, causing gas and indigestion and impairing the absorption of useful nutrients. Most commonly, these include FODMAPs, a sort of fermentable short-chain carbohydrate that is poorly absorbed by the human intestine. Other anti-nutrients include gluten, lectins, and phytic acid.  

Minimize your consumption of the following foods:

• Wheat and barley, which contain gluten and FODMAPs
• Beverages that contain significant amounts of calories (other than protein shakes)
• Brown rice, which contains phytic acid
• Legumes such as beans, lentils, and peanuts. These are rich in lectins, or the reason that beans cause gas.
• Any obvious junk food like ice cream, candy, etc.
• FODMAP-rich vegetables such as onions, garlic, artichokes, asparagus, cauliflower, green peas, mushrooms, and sugar snap peas
• Added sugar and sugar alcohols
• Alcohol  
  

How to Eat on a Vertical Diet

While most foods are acceptable on a vertical diet, the idea here is to deliberately add in those which are rich in calories and easily digestible. Generally, this means natural carbohydrates and fatty meats.  

Add in as much of the following as you can:

• Hormone-free fatty and red meats such as pork belly and fatty cuts of beef, and bison
• Fatty fish such as salmon
• Beef tallow, olive oil, coconut oil, and other minimally-processed fats
• Eggs
• Full-fat dairy (consider lactose-free milk though)
• Fruit, but especially low-FODMAP fruits such as cantaloupe, grapes, kiwi, oranges, pineapple, and strawberries
• Low-FODMAP vegetables such as green beans, eggplant, bok choy, bell peppers, carrots, cucumbers, lettuce, potatoes, sweet potatoes, tomatoes, and zucchini
• White rice and corn
• Sprouted or sourdough breads, which don’t have most of the anti-nutrients present in other wheat-based foods
• Sprouted or thoroughly-soaked legumes, in modest quantities. Canned beans work well as long as you rinse them thoroughly.  
• Hormone-free poultry, but ideally fatty cuts of meat.
  
  

Perhaps surprisingly, nuts aren’t on this list due to their tendency to promote systemic inflammation. They aren’t disallowed, but you shouldn’t go out of your way to eat a lot of them.

Related: 5 Ways to Eat More Calories When You're Trying to Bulk Up

Pros and Cons of a Vertical Diet

A vertical diet will allow you to eat a lot of calories to support muscle gain and/or a very high activity level while keeping your digestion healthy. It’s especially useful for athletes who suffer from irritable bowel syndrome (IBS) or other digestive issues.

On the other hand, it can be expensive due to the focus on high-quality protein sources and avoidance of cheaper, high-calorie foods in general. It can also be restrictive when eating out or eating socially.  

Ways to Modify the Vertical Diet

Not all of these rules are equally important, so if you find the vertical diet overly restrictive, you can apply the 80/20 rule to it.  

The most crucial parts are avoiding obvious junk food, liquid calories, alcohol, wheat, and barley (other than sprouted and sourdough breads). You can avoid those altogether, but minimize the other non-beneficial foods without completely eliminating them.

Related: Should Athletes Follow a Low-FODMAP Meal Plan?

Another approach that you can take is to test different foods individually and see which ones cause digestive problems for you. Different people have different levels of tolerance for various anti-nutrients, so you may find that one or two of the “avoid” foods are actually alright for you. Many people, for instance, have no trouble with beans or brown rice.

Finally, as with any specific meal plan, occasional cheat meals are fine, especially if you’re an athlete who needs a lot of calories. As always, the ideal time for a cheat meal would be in the few hours following a weight training session.