IIFYM – Can You Really Eat What You Want And Get Lean?


Unless you’ve been living under a rock for the last couple of years you would have heard of “If It Fits Your Macros” or IIFYM. You might have even tried it. By utilising a more flexible approach it allows the individual to eat whatever they want provided it fits into the calorie and macronutrient (protein, carbs and fats) numbers as set out for their goals. The ever growing diet protocol promises fast, sustainable results for fat loss and body composition goals. Sounds great on the surface right? But is it all it’s cracked up to be?

Does IIFYM really work?

The Calorie Conundrum
To a certain extent IIFYM looks at calories as calories and in recent years the IIFYM debate seems to revolve heavily around this subject. In the simplest terms, yes a calorie is a calorie. One gram of protein has four calories, one gram of fat has nine calories etc. And yes you could eat poor quality nutrition all day, and provided you kept in an energy deficit, you would lose weight. Notice I said “weight” there. If you wanted to lose fat, whilst retaining lean mass and promoting health, a different approach is needed.

When you start to dive deeper you’ll notice calories aren’t just calories. To dumb it down like this wouldn’t be wise, especially for the individual that wants to dramatically change their body composition and health.

Take for example carbohydrates and the effect different choices can have on blood sugar and insulin secretion. An individual training for fat loss goals might have a target of say 150g of carbohydrates to hit a day. IIFYM says they could consume any carbohydrate source including potatoes, brown rice, broccoli, ice cream or pasta as long as it adds up to 150g. Hell why not just eat ice cream all day?

The problem here lies in the fact that each of those carbohydrate sources mentioned above will effect blood sugar and insulin differently. Ice cream will send it on a steep roller coaster ride. Whereas brown rice and broccoli for example will be much more controlled and steady. For fat loss remember it’s essential for not only an energy deficit, but also controlled levels of blood sugar and insulin release throughout the day. Excess insulin inhibits the fat burning process and could encourage you to store more fuel as fat when in a calorie surplus.

It’s also worth touching on the thermogenic effect of food (TEF) here. Different foods will require a certain amount of calories to break them down. Thus positively or negatively impacting your total daily energy expenditure (TDEE). Sugary carbs would be broken down faster than fibrous carbs for example. Meaning less calories would be needed for the process.

Obesity, Food Choices And Relapses
Absolutely worth mentioning and I won’t beat around the bush here, I’ll say it how it is. IIFYM is certainly marketed at overweight and obese individuals. The thought that you can still eat the foods currently consumed on a daily basis and see a result appeals to them. It sells. But those foods are a huge part of reason that individual has ended up in that situation. Do you think it’s wise to keep them in the diet on such a frequent and regular basis? Think of it like the recovering alcohol going out for a pint after their weekly AA meeting.

Other Implications To Consider
Digestion is a topic that often gets brushed over with IIFYM. It goes without saying your body is going to struggle to optimally digest foods if your feeding it with crap every meal. Even if you are fitting it in with your numbers! Clean and natural food sources such as meats, fish, eggs, vegetables and nuts all come with the enzymes present needed to effectively break them down. Processed foods don’t, they have them removed. This is one of the reasons why natural foods rot and breakdown quickly, whereas processed foods don’t.

Leading on from digestion we come to micronutrients. These are vitamins and minerals found in foods. If you’re using your carbohydrate and fat daily quota to eat pizza and ice cream, chances are you’re not going to be taking in adequate micronutrients. Not only this, you will also struggle to digest and absorb them effectively anyway. Potentially leaving you exposed to various deficiencies.

What About Previous Successes And The People That Swear By It?
I’ve made a very interesting observation on those that are advocates of IIFYM. You can try this experiment to. If you search for #IIFYM on any social media platform such as Instagram or Twitter a large percentage of the results from clients and the trainers that preach it all have something in common. They’re all fairly lean individuals to begin with. I don’t think IIFYM got them in that shape either, I think they’re just naturally lean people. Remember to a certain degree the leaner you are the more metabolically flexible you are. The more efficiently your body can deal with and handle excess blood sugar and insulin.

Sorry to rub it in here, but this will demonstrate my point perfectly. I’m currently sitting at around 9% body fat. I could probably eat junk food every day over the next few weeks and provided I didn’t stray too far above my TDEE it wouldn’t effect me overly. I’m relatively sensitive to insulin, my body can deal with spikes in excess blood sugar and psychologically I don’t feel the need for more once I’ve had some if that makes sense? Others with a higher body fat level would struggle.

As far as previous successes go, what can I say? You can’t argue it hasn’t worked for some people. So as a dietary protocol for fat loss it does work. This is provided it’s not abused. For the best version of you, you can’t just eat crap all day provided it “fits in with your macros”.

Will it work for you? Maybe! Is it for every one though? I doubt it very much.

Take Home Points
Whilst I’m all up for a certain level of flexibility within the diet (it’s exactly how I get results with my clients and sustain them!). A free pass to eat whatever the hell you like provided it fits within the numbers? I don’t think it’s smart. There needs to be a middle ground. There’s too much of a high risk of relapses, adherence issues and poor nutrient quality. All resulting in yo-yo dieting and lowered health and performance.