First off, a primer. When CrossFit Founder Greg Glassman was formulating the methodology of CrossFit he came up with a pyramid that represented the most necessary to the least necessary fundamental parts of fitness. At the base of that pyramid is nutrition. On the next level up is metabolic conditioning; in the middle is gymnastics; second from the top is weightlifting and throwing, and at the top is sport.
Why is nutrition the base? When we think of CrossFit we think of the world’s best fitness method, but for most people fitness begins and ends with their 30-60 minutes of working out. This short-term view is a big part of why so many people fail to meet their fitness goals. Nutrition provides the building blocks by which our body is able to change. Unfortunately that goes both ways. When our nutrition doesn’t align with our goals, we pretty much always see stagnation or reverse in progress at some point. For beginners, they may be able to see change for a while, but they will eventually plateau. For more experienced athletes (and by athletes I mean anyone who regularly trains for the purpose of a goal whether in sport or fitness), this is often the limiting factor to more elite performance, less body fat, and/or more muscle.
Good nutrition provides the ideal environment for the body to recover from tough workouts and be ready to train again the next time. This provides the fastest (natural) pathway towards our fitness goals. If your body has enough macro- and micro-nutrients to support the amount of stress (good stress from your workouts) put on it, it will grow stronger incrementally and you will continue to see better performance, more energy, gains in strength and muscle, and less unwanted body fat. In order to keep causing adaptation (aka favorable changes in your body composition or performance) you need to continue to add new and greater stress to the body. This is how a diet that stresses the body rather than helping it recover will eventually end up causing a plateau. Your body can only take so much stress before it starts to cause unfavorable adaptations. In terms of performance, you will start to see a plateau in strength gains or injuries. In terms of physical changes, fat loss may start to reverse. You can no longer continue to be either eating too few calories where you lack the correct macro- and micro-nutrients or too many of the wrong calories that are not used for recovery and are just stored as fat.
This doesn’t have to be hard though. You don’t have to eat boiled chicken breasts and broccoli for lunch and brown rice and tilapia for dinner every night to be healthy (yuck!). Start with increasing the amount of the healthy things you do like to eat. Like steak? Buy a steak from the store for less than it would be to go out to eat. Do you have a sweet tooth? Eat whole fruit until your stomach is about to burst. Pick whatever vegetables you do like and start eating more of those. Find out ways to get more leafy greens, whether through a smoothie or or greens supplement if you don’t like salads. Mix in fruit and a little stevia with plain greek yogurt for a fantastic dessert! It doesn’t have to be hard, but it does take planning so sit down and take 30 minutes to think more critically about your choices and how they are affecting your health and fitness. If you need help, ask for it! There are many resources available to help you eat healthier, and if you have a special condition than seek a professional. You have to eat anyway, so find a delicious, long-term way of eating that will help you meet your fitness goals!