Metabolic Flexibility

Understanding Metabolic Flexibility

In April we slowly but surely made our way through some of the top line concepts of metabolic flexibility. In a nutshell, metabolic flexibility is the body’s ability to use fats when they’re present, or carbohydrates when they’re present – your body’s ability to manipulate what sources it uses for fuel and energy.

So here’s a quick example: if you take in a meal of carbs first thing in the morning your body will stop using fats for energy, and will start using the carbs you just consumed. If you have a high amount of carbs your body will use carbs. Likewise, if your body has a high fat content from a meal it will use fat. Remember from this post, if your carbs are up, insulin is up. Insulin says “use carbs, not fat.” As soon as the amount of carbohydrates lower in your body insulin says “I need something else for fuel” and switches to fat. I hope this makes sense, if it does NOT please write in the comments or send me a direct message here.

I’m assuming you probably want to know – when do I eat fat? When do I eat carbohydrates? We kind of went into the carbohydrate timing here. But let’s go a little further. What you eat and when you eat it is important.

When you’re using high carbs you stop using fats. When you eat a carb and a fat together, fats interfere with the ability of carbs to enter the muscle. This is metabolic inflexibility – your body’s ability to use both fuel sources independently. So, you should still eat both carbs and fats, but NOT in the same meal. Example: If you’re having an omelet with veggies, a little bit of cheese that’s great, you’re using that fat for fuel. If you add in pancakes or French toast (carbs) then your body will use the carbs and the fat will go into reserves and you’ll experience a conflict.

Let’s talk about breakfast – the most important meal of the day. The bottom line is this. People who skip breakfast tend to gain fat. They just do. You’re hungry. You eat more calories and you gain weight. This is how it goes. Breakfast programs your metabolism to be flexible or inflexible for the rest of the day. So I offer you this advice if you are looking to improve your body composition, lose weight, and build muscle. Please note: if you are an endurance athlete you will need to follow a different protocol because your body will need more carbohydrates to give yourself the energy you need for your longer endurance training.

When you’re waking up you may want considering eating FAT and (moderate) PROTEIN. You wake up, you’re in a low energy state, the protein will get digested quickly (and be converted into carbs if you eat too much of it, hence why you should have a moderate amount) but the FAT will slow that digestion down. You feel fuller and you’re more satisfied. Your metabolism is revved for the day. I’ve found that by doing this I have a ton of energy, and then am able to use my carbohydrates towards the middle of the day or around my workouts.

Carbohydrates do not directly build muscle, they’re just fuel. Take in enough carbs to give yourself the energy you need to fuel your day and your workouts. If you’re in carb excess you shut down your ability to use fat as fuel – you don’t want this. You then store fat and you gain weight. You know? You should eat as many carbs as your body can tolerate. Proteins build muscle, fat provides the energy that fuels that muscle. Carbs give you the energy to live your life, workout, and

What can you take away from this? What you eat and when you eat it matters. Explore what your body reacts to, keep track of your foods, meals, energy, physique. It takes time, but stay mindful and stay focused!

Want more? Check it. Or this (please don’t let the hideous picture that pops up right away deter you, it’s a very informative article).

Image here.


  1. Thanks for all this great info, it’s kind of blowing my mind. But questions! First: When you say “moderate” protein with breakfast, what does that mean? A couple eggs?
    Also, this is somewhat of a tangent, but I’ve just started running longer distances to train for half marathons, and I notice a lot of caveats in healthy eating info about long-distance athletes needing more carbs, as you’ve noted here. What level of training classifies one as a “long-distance athlete”? I don’t think I’m there yet, but as I increase my distance runs over time, I don’t want to under-fuel my body.
    Also … so this means peanut butter toast is a big fat NO? I’m in mourning.

    • Hey Emily! Thanks for the comment. A few things – race nutrition is SO personal, so I hesitate to say what you “should” do. When I was training for the marathon I had a Van’s protein waffle with almond butter and that worked great for me. Metabolic Flexibility is all about efficiency, but can be a bit extreme. When I’m just focusing on being mindful and staying healthy I’ll have steel cut oats in the morning and egg whites. When I’m preparing for a photo shoot or am looking to shed fat quickly I’ll put this concept into place. If you’re doing half marathons right now I don’t think that qualifies for longer distances, once you’re reaching the 14+ mark then you should really play around with your race nutrition. If you’d like to discuss more please submit a contact form and I’ll respond to you directly via email! Thank you!

  2. Thanks to the link to my T-mag article on metabolic flexibility. I really appreciate it! Mike T

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