It’s late in the afternoon and time for your fourth meal of the day: Six ounces of grilled chicken, one cup of rice, and a mix of green veggies. Sound familiar? And monotonous? Even the most dedicated bodybuilder or physique competitor dreads the same old routine. Hence, flexible dieting, or “If It Fits Your Macros” (IIFYM), has taken root in fitness culture and gone mainstream. IIFYM is a based on the principle of “calories in, calories out”, which means you won’t gain weight, regardless of food choice, so long as you don’t exceed your total caloric needs for the day. For the fitness enthusiast, IIFYM takes this concept a step further by taking macronutrient requirements for building muscle and fat burning into account.

Suddenly, pizza, burgers, and ice cream are all back on the menu. But there’s a lot you need to know before you dive in. On the following slides, we’ve culled five crucial points from our panel of experts. If you decide that IIFYM is right for you, you can calculate your daily needs using the Muscle & Fitness food pyramid. Then, be prepared to write down everything you eat and calculate the macros throughout the day; IIFYM won’t work for you if you’re not careful about measuring your portion sizes.