In this blog, I’m going to discuss Insulin Sensitivity, and why it matters during fat loss and muscle building. This blog is for education purposes only.

Introduction

When it comes to changing your body composition, most people focus on very low calories or doing loads of cardio. But one factor that is often overlooked is insulin sensitivity. Insulin is often labelled as a “fat-storing hormone”, but it is far more complex than that. It plays an important role in regulating blood glucose, energy storage, muscle recovery and how your body uses the nutrients you eat.

So, why does insulin sensitivity matter when you’re trying to lose body fat and/or build muscle?

Let’s have a look…

Firstly, what Is Insulin Sensitivity? Insulin is produced by the pancreas and helps move glucose from your bloodstream into tissues such as your muscles and liver, where it can be used or stored. Insulin sensitivity refers to how effectively your body responds to insulin.

Good insulin sensitivity means your body can manage glucose effectively, with your muscles able to take up carbohydrates efficiently and replenish muscle glycogen following exercise. However, insulin sensitivity can be influenced by a number of factors including physical activity, muscle mass, body fat, diet, sleep, stress and energy balance.

Insulin is produced by the pancreas and helps move glucose from your bloodstream into tissues such as your muscles and liver, where it can be used or stored.

Insulin sensitivity refers to how effectively your body responds to insulin.

Good insulin sensitivity means your body can manage glucose effectively, with your muscles able to take up carbohydrates efficiently and replenish muscle glycogen following exercise.

However, insulin sensitivity can be influenced by a number of factors including physical activity, muscle mass, body fat, diet, sleep, stress and energy balance.

 

Insulin Sensitivity During a Fat Loss Phase

The foundation of fat loss is a sustained calorie deficit – consuming fewer calories than you expend over time. At Rehabify, using our app, we calculate your calorie deficit for you using your data and create you a meal plan to these specific macros.

However, improving your insulin sensitivity can support the process. As part of the calorie deficit, we not only focus on what we eat, but how much energy we expend. Regular resistance training and physical activity can improve your muscles’ ability to take up glucose. This is one reason why strength training should remain a priority during a fat-loss phase.

In addition to this, a lot of people view carbohydrates as the enemy during a fat loss phase but actually this is not the case. Carbohydrates are the body’s key energy source and they can support training performance, recovery, muscle glycogen stores (fullness) and muscle retention (maintaining muscle). What matters most is how they fit into your overall calorie and nutritional intake.

The goal during fat loss should not simply be to make the scales go down. Ideally, we are looking to reduce body fat while maintaining as much muscle as possible, which comes from a combination of: Calorie deficit + resistance training + sufficient protein + regular movement is what works!

On the other hand, avoiding an aggressive calorie deficit is also very important, because this can negatively affect training performance, recovery, sleep and your ability to maintain muscle. Furthermore, it is just not sustainable long-term!

 

Why Your Starting Point Matters When You Are Building Muscle

Once you have completed a fat loss phase, the next question is often: “How do I start building muscle without gaining loads of body fat?” And the key here is your starting point.

Beginning a muscle building phase (or known as a gaining phase) from a relatively lean and metabolically healthy position can be advantageous. Higher levels of excess body fat, particularly visceral fat, are associated with poorer insulin sensitivity.

Therefore, by improving your body composition first, you create yourself a more favourable body composition for managing the additional calories introduced during a muscle building phase.

This does not mean you need to get extremely lean, nor does it mean someone with a higher body fat percentage cannot build muscle.

Instead, the goal is to reach a sustainable, relatively lean starting point before gradually increasing calories. There is no “perfect” starting point, but the leaner and more responsive, the better.

Think of it as creating a better foundation – the more solid this, the better it is.

If you go into your muscle building phase with better insulin sensitivity, already good exercise/training habits, a strong nutritional foundation and adherence, better awareness of your calorie requirements, and lower levels of excess body fat, this can make the transition into a calorie surplus much easier to manage and promotes longevity.

 

Don’t Confuse “More Calories” With “More Muscle”

One of the biggest mistakes people make after finishing a fat loss phase is dramatically increasing their calorie intake. We often increase your calories to 250 above your maintenance initially and monitor the response.

Going from a calorie deficit straight into a large surplus, does not mean you will suddenly build muscle faster! Muscle building is a slow process. Your body can only build muscle at a certain rate (different for everyone), so consuming significantly more calories than you need can simply result in unnecessary fat gain, and cut your muscle building phase short.

Instead, a small and controlled calorie surplus is generally a more sensible approach – gradually increasing your food intake and monitor how your body responds. This is why weekly check-ins are important as we can monitor that response here.

We look at your photos/body composition, gym performance/exercise output, energy levels, sleep, recovery, scale weight, and body measurements.

Therefore, if your scale weight is not increasing and performance is not improving, you may need slightly more calories. On the other hand, if scale weight and body fat are increasing rapidly, your surplus may be too large. The key is to roadmap 8-12 weeks of slow and steady increases across the board.

 

The Transition – From Fat Loss to Muscle Building

A simple approach that we often take is:

Finish your fat loss phase

Reach a sustainable level of body fat that we are both happy with rather than chasing extreme leanness. This make take a couple of weeks or a couple of months, everyone responds differently.

Establish your maintenance

Worked out specifically to you, it may be worth spending some time understanding how many calories you need to maintain your body weight.

Keep exercising and training

Continue progressive resistance training and maintain your activity levels.

Introduce a small surplus

Starting with a 250-calorie surplus (above your maintenance), gradually increase calories rather than dramatically increasing them.

Monitor your response

On a weekly basis, track your exercise/gym performance, scale weight, measurements, overall energy levels, sleep, and recovery.

Adjust when necessary

Use your progress data to determine whether calories need to increase or decrease, and/or whether your output is needs to be changed.

Longevity

The key is to NOT yo-yo between a fat loss phase and muscle building phase, roadmap the journey and play the long game, the results are waiting for you!

 

Conclusion

Insulin sensitivity refers to how effectively your body responds to insulin and this can be improved by a number of factors including increasing your physical activity, increasing muscle mass, reducing body fat, diet, sleep, low stress levels and your energy balance.

You do not need to eliminate carbohydrates to lose body. Carbohydrates are the body’s key energy source and they can support training performance, recovery, muscle glycogen stores (fullness) and muscle retention (maintaining muscle). What matters most is how they fit into your overall calorie and nutritional intake.

Reduce body fat levels. Build the strong foundation. Then build the muscle. Repeat this process over and over for a long time… 💪🏻