Intermittent Fasting...Yes or No?

Intermittent fasting, keto, paleo, south beach, (insert newest fad here) all "work" IF AND ONLY IF one requirement is met--Energy Balance...Calories in vs calories out. There is NO diet in existence or even possibly in existence until the laws of thermodynamics are invalidated that avoids this requirement.

If one of those models works well for you, and helps you take in fewer calories than you expend, awesome! We use lots of tools in our toolbox, and I love having options that help people fit the energy balance requirement into real life. I am not against any diet model which helps someone achieve that.

HOWEVER, our approach here at 15 Minute.Fitness focuses on one thing that most diet models do not. We make a distinction between "losing weight" and "losing fat". All "weight loss" is not equal.

We hold to the long-term strategy that the only way to ultimately free yourself from the yo-yo diet loop that most are stuck on is to build muscle tissue which raises Resting Metabolic Rate for life. If you build lean muscle tissue, you will be able to eat MORE food (and I'm not just talking rice cakes and salad) for the rest of your life because you have fundamentally altered your metabolism for the better.

If you don't change your metabolism, then you are stuck on a permanent diet--for life. You have a life sentence of rice cakes, salad and air sandwiches--without bread!

So, for us, in order for your "fat loss program" to set you up for more than a short-term dip on the scale, your diet model needs to support your long-term project of building muscle. That means #1) High Protein boluses spaced out at regular intervals throughout the day, #2) Appropriate caloric intake for where you are in the muscle-building/fat-loss cycle (it is not a linear process), #3) Adequate micronutrients and fiber for overall health and to support muscle protein synthesis. Any model which checks those boxes gets a green light from me. Any model which fails to check those boxes (and any attempt to "diet" without strength training) fails to meet our standards as a measure supporting long-term success.

So, what is the verdict on Intermittent Fasting? There is nothing special about it. I do it every day. I fast at least 8 hours while I sleep. (Unless I'm on a dedicated, determined muscle build, when I get up in the night for a midnight snack) 　.

The main problem with Intermittent fasting for us is that skeletal muscle tissue is made of protein. Of the three macronutrients (Protein, Fat, Carbohydrates), protein is the only one that is not "stored" in the body for later use (beyond a VERY small amino acid pool in the liver). That means, you need protein boluses at regular intervals. That means NO long intervals without protein. So, fasts longer than that which happens naturally while you sleep are NOT recommended for our approach outlined above. You may lose "weight" but much of that weight will be muscle tissue, and you may end up "Normal Weight Obese." (Traditionally, this was termed "skinny fat".)

If your goals are long-term rather than short term, I would not recommend intermittent fasting.

If a modified form of Intermittent Fasting (with protein boluses in the middle of your "fast") helps you manage calories, go for it! Just make sure all the boxes above are checked first! The last thing you want for health or body image is to sacrifice muscle tissue--quite the opposite.