What You Should Know About Insulin

Let's talk insulin.
Mention the "I word" to a low carb dieter, or even a clean eater, and you can virtually see them turn white as the blood drains from their face in abject horror.
To them, insulin is the big bad guy in the nutrition world.
They refer to insulin as "the storage hormone" and believe that any amount of insulin in the body will immediately cause you to lay down new fat cells, put on weight, and lose any degree of leanness and definition.
Fortunately, that's not quite the case.
In fact, while simplifying things in terms of nutrition and training can often be beneficial, this is a gross over-simplification of the role of insulin within your body, and the truth is entirely different.
Far from being the dietary devil, insulin is really nothing to be afraid of at all.
What Insulin Does
The first part of the insulin worrier's claim (that insulin is a storage hormone) is true - one of insulin's main roles is to shuttle carbohydrate that you eat around the body, and deposit it where it's needed.
That doesn't mean that all the carbs you eat are stored as fat though.
You store glycogen (carbohydrate) in your liver, your muscle cells and your fat cells, and it will only get shoved into those pesky adipose sites (fat tissue) when the muscles and liver are full.
Additionally, unless you're in a calorie surplus, you simply cannot store body fat.
Look at it this way -
Insulin is like the workers in a warehouse.
Calories are the boxes and crates.
You could fill that warehouse fit to burst with workers (insulin) but if there are no boxes (calories) to stack, those shelves won't get filled.
So if you're burning 3,000 calories per day, and eating 2,500 calories (or even 2,999) your body can't store fat. It doesn't matter if all those calories come from carbs or sugar, you simply won't store them, as your body needs them for fuel.
Granted, this wouldn't be the world's healthiest diet, but as far as science is concerned, it comes down to calories in versus calories out, NOT insulin.
It Isn't JUST Carbs
People fret over carbs having the biggest impact on insulin levels, and how carbohydrate (particularly of the simple/ high-sugar/ high-GI variety) spikes insulin levels, but plenty of other foods raise insulin too.
Whey protein, for instance, is highly insulogenic, and can cause a spike, particularly when consumed post workout.
Dairy foods too will have a relatively large effect due to the natural sugars they contain, and even fats can raise insulin levels.
Additionally, the insulin effect is drastically lowered when you eat a mixed meal - i.e. one that contains carbs plus protein and/ or fat.
This slows the digestion and the absorption of the carbs, leading to a much lower insulin response. Add fibre into the mix too, and the raise in insulin is minimal, so even if we were worried about it before, the solution is simple - eat balanced, nutrient-dense meals, and you need not worry.
Insulin Builds Muscle
Going back to the idea of insulin being a storage hormone, and the notion that it delivers "stuff" to cells:
Fancy taking a guess at what else it delivers, beside carbohydrate?
It delivers nutrients to your muscle cells.
Therefore, if you're forever trying to keep insulin levels low for fear of fat gain, it's highly unlikely you'll build muscle optimally. It's for this reason that I'd never put clients looking to bulk up and make lean gains on a low-carb diet.
No Insulin Can Still Equal Fat Storage
Contrary to all those low-carb diet practitioners once again, it is possible to store fat when insulin levels are low.
Dietary fat when consumed in a caloric surplus is actually converted to body fat tissue far more readily than carbohydrates are, showing that once again, fat gain or fat loss comes down to calories in versus calories out, not insulin levels.
Why low-Carb (and Low-Insulin) Diets "Work"
Many folk will point towards the scientific and anecdotal evidence of low-carb diets working as reasoning for keeping insulin levels low.
I won't argue - a low-carb diet, where insulin release is kept to a minimum can certainly work, but this has very little to do with the hormone itself.
When you cut carbs, you typically cut calories, putting you into a deficit.
Additionally, the average person will eat more protein and more vegetables when going low-carb, so they feel far fuller and eat less. Plus, protein and fibre both have a high thermic effect, meaning they actually burn more calories during the digestion process.
Bottom Line: Insulin - Not So Bad After All
You don't need to worry about insulin if you -
Train hard and regularly
Eat a balanced macronutrient split (i.e. ample protein and fat, and carbs to suit activity levels and personal preference.)
Are relatively lean.
Eat mostly nutrient-dense foods.
Have no issues with diabetes.
You can still store fat with low insulin levels, and you can burn fat and build muscle when insulin is present.