Is Insulin Stopping You From Losing Fat?

Spiking insulin, hyperinsulinemia, insulin resistance, impaired glucose tolerance, however you want to name it, the common perception amongst the general public is that the hormone insulin impedes fat loss.

Why?

Because it’s seen as a ‘storage’ hormone.

Produced by the beta cells of the pancreas, insulin is released every time we eat, in higher amounts when we have a larger meal or have a meal that contains more carbohydrates.

It’s primary function is to act as the ‘key’ to the door of our muscle cells – which then allows glucose (carb) molecules to enter and to be stored as muscle glycogen.

This in essence, lowers blood glucose levels as that is where the carbs we eat will initially end up.

Having prefaced this with the above, it’s easy to see why some people have developed this idea that insulin shuts off fat burning and therefore anything that promotes insulin should be avoided i.e. refined carbs/sugar.  

 Now, time for some science.

Mechanistically, all of the above isn’t wrong.

As we eat and as insulin is released, we are in fact in ‘storage mode’.

We’re not really burning a huge amount of fat, assuming that you’re sat down whilst eating and you continue to sit after finishing (this is important, which we will come back to).

But, the big ‘a-ha’ moment that many do not consider is actually a pretty simple and easy one to grasp.

When insulin is high, we store carbs/calories.

However, when we’re not eating, we have other hormones that do the opposite job.

Glucagon is the main opposing hormone to insulin where it’s main function is to release those stored glucose molecules back into the bloodstream to be used.

Maintaining optimal glucose levels is important to feed the brain.

So, when blood glucose levels go up, insulin brings it back down, when glucose levels drops low, glucagon (which is produced by the alpha cells of the pancreas) brings it back up.

Simple pimple, right?

It’s as though the pancreas knew what it was doing all along…

This is the first point we can make against any insulin enthusiasts out there about carbs/insulin storing fat and blocking fat burning as they forget to mention how glucagon does the opposite thing by mobilising and releasing the carbs/calories back into circulation for energy.

So, you’re probably now wondering ‘ok, I get that the body has counter-regulatory mechanisms in place to safeguard my glucose levels, but what about fat burning’?

This second point here is a crucial one.

Fat burning is not the same thing as fat loss…

Let me explain using my favourite ‘bank account analogy’.

Let’s say for argument’s sake that instead of being paid at the end of every month, your monthly salary is broken up into tiny daily payments and you are paid 3x a day.

In the morning, in the afternoon and in the evening.

Let’s also say that you get paid in cash and have to deposit it in the bank at those 3 specific times every single day.

So, you head to the bank in the morning and make a payment, you are slightly richer.

But let’s say on your way back, you pick up a coffee and a fruit bowl. Instantly poorer.

You make your lunchtime payment, richer again.

In the evening, you make your last payment of the day but then get whacked by your mortgage coming out.

You are getting ‘richer’ and ‘poorer’ all day, every single day.

Obviously what matters most in the context of your finances here is – how much are you spending vs how much are you saving (what your salary is).

It’s virtually the same thing when it comes to fat burning and fat storage.

The moment you eat and insulin goes up, you are storing fat and getting fatter.

But when you’re not eating, glucagon and other hormones like cortisol, adrenaline and noreadrenaline are releasing carbs/fats to be used as energy – promoting fat burning.

Especially when we are exercising.

You are gaining fat and burning fat all day, everyday.

What determines whether you are losing fat or not is determined by how much you have gained vs how much you have burned. Just like your finances.

How do we do that?

Energy balance.

Calories in vs calories out.

Going off on a slight tangent but still very much in-line with this carbohydrate-insulin model of obesity that we’re talking about (which has been disproved) – there is one scenario where I have a lot of sympathy for when it comes to struggling with fat/weight loss and using elevated insulin levels as the reason.

PCOS, or polycystic ovarian syndrome.

Insulin resistance is a hallmark feature of this condition which exacerbates fat gaining and a host of other unpleasant symptoms.

Often, women with PCOS are led to believe that because of their insulin resistance, they shouldn’t be eating carbs and/or anything too sugary as it’ll spike their insulin.

Firstly, if this were true, then surely type 2 diabetics who are majorly insulin resistant shouldn’t be able to lose weight/fat eating carbohydrates too?

You only need to look as far as the Direct trial, one of the biggest type 2 diabetes remission studies to date and what their protocol was for patients.

It wasn’t to follow a low carb diet, they had their patients follow a low calorie (800) diet (provided by the Cambridge diet) and lo and behold, tons of them achieved weight loss and remission.

One final (and important) point.

For some PCOS patients, removing carbs from their diets works like a charm. But not for the reasons they think.

Removing a whole food group from your diet is bound to leave you eating less calories as a result. Especially when you’re left with protein and fats to eat. The two most satiating macros of the three. 

While they think it’s because they lowered insulin, it’s actually because they consumed fewer calories and pushed themselves into a calorie deficit.

However, for other PCOS patients (about 50%), reducing carbs and even calories won’t always work initially.

Why?

Because they have a lowered BMR (basal metabolic rate).

Without going into too much technical detail at this point, a lowered BMR essentially means a slower metabolism.

Some studies suggests this could range from 14-40% (Georgopoulos et al, 2009).

So what does this mean in practical terms?

It means that when you go online to figure out how many calories you should be eating to lose weight, this could be in excess by a whopping 40%!.

In other words, a 30 year old female who is 5 foot 4 and weighs 77kg should ‘on paper’ have a BMR of 1615 calories.

In the worst-case scenario, a 40% reduction of this would be 969 calories!

So really, figuring out how many calories would constitute a calorie deficit is usually the confusing and tricky part.

References 

https://www.sciencedirect.com/science/article/pii/S001502820801008X