IIFYM (If It Fits Your Macros) has emerged as one of the top nutritional approaches for athletes, bodybuilders, and weekend warriors alike to implement in their day to day life to support their performance, body composition health.
There is no such thing as "clean" foods or "bad" foods when it comes to your body composition, essentially, the body does not process the carbohydrates from a donut differently than it processes the carbohydrates from a sweet potato. Optimal body composition is achieved and maintained by a balance of macronutrient targets and caloric intake - you can choose whatever foods you like to fill those numbers.
Basically, as far as body composition is concerned, if you eat the sweet potatoes and oatmeal the result is the same as if you were to eat the exact same amount of grams of carbohydrates + fat from donuts & pizza. Any of these people will tell you that they have the occasionally treat and it doesn't derail them from their body composition & athletic goals! 't long as the caloric intake is equal, and you hit your macros - you will progress.
Losing body fat is more about limiting excess calories, increasing your protein, and eating for your needs rather than eliminating specific foods. IIFYM gets rid of the guilt, and allows you to enjoy food again. No wonder it's so popular!
Ok, so I've got your attention? But what about your health?
Obviously I am not advocating that you should demolish a party size pizza from your local pizza joint - whole 'health' foods full of micronutrients are going to contribute towards an overall healthier you. However, I don't think there is a need to demonize pizza, ice cream & beer or allow those foods to have the power to make you feel guilt. If you can make it fit into your daily macros allotment - it will not negatively affect your body composition!
But what about gluten? The GI index?
Pending no pre-existing health concerns, the GI index & gluten free foods are irrelevant when it comes down to body composition. This is basic science - your insulin is going to spike no matter what you eat. For the general population - the thing that matter most is your total daily caloric intake and eating the specific amount of carbs/fats/proteins your body needs. Your body will use the energy that it needs based on the demands placed upon it. Low GI, high GI - it doesn't matter - it just matters that you do not eat either in excess. I do think that for athletes in the top 1% of their field (we're talking olympic athletes, pro bodybuilders preparing for a show, CrossFIt games level athletes) could have a positive effect from eating lower glycemic foods, nutrient timing etc due to hormone levels but this is truly not relevant to most of us. Often people get too caught up in the 1% (like taking supplements) and forget about dialling in on the pillars of nutrition - carbs/fats/proteins.
But I'm scared of carbs?
Carbohydrate is a science-y word for sugar. Seriously. The end result of your bread, your donut, your sweet potato and your oatmeal are essentially the same. The body breaks them down into glucose. The body needs these sources of glucose for energy. Anything the body does not use for energy is then stored as fat. Whether you are lying on the couch or you are a hard-working farmer - we all expend energy in a day - the overall amount varies and that is why everyone's individual macronutrient needs differ.
You need carbs. The primary goal is to provide energy for the body to do what it needs to do - but you need them for sanity, for longevity, to make food enjoyable, to make your health, performance and body composition sustainable.