Insulin and glycogen in muscle growth
Insulin isn’t just the “fat-storage hormone.” If you train, it’s important to understand when it helps move glucose into your muscles and when excess energy simply becomes a reserve.
A simple truth: carbohydrates don’t all behave the same way in the body. What matters as much as the amount is the food they come from and what you eat alongside them.
Why do insulin and glycogen matter?
The body can store only a limited amount of glucose. The liver, for example, can store about 100 g. When more carbohydrates come in than the body needs at that moment, it has to do something with the surplus.
Insulin helps move glucose from the blood into cells. When there is room in the muscles and liver, the glucose goes into energy stores. When there isn’t, some of it can move toward fatty acids and triglycerides. The estimate of “around 10%” mentioned in the original text suggests that during the conversion some of the energy can end up stored as fat.
This is exactly why names such as Dr Atkins began to emphasize carbohydrate-restricting diets. But the question isn’t only whether to eat carbohydrates or not. The better question is: which carbohydrates are you eating?
Glycogen comes into play here too. Glycogen is stored carbohydrate that the body can use when blood sugar drops or when you need energy quickly in a workout. The original text describes it as the opposite of insulin; in modern terms, glucagon is often the hormone named in that role, helping to raise blood sugar. The idea stays the same for the trainee: the body is constantly swinging between storing and using.
How does insulin respond to carbohydrates?
Simple carbohydrates often come from refined foods: pizza, bread, baked goods, candy and the like. They break down quickly and the glucose reaches the blood fast. In response, insulin is released, helping move that glucose into the muscles and other tissues.
When your muscles’ energy stores are emptier after a workout, the picture is different from eating candy on the couch in the evening. Training makes the muscles more receptive. That is also why the original text stresses that within half an hour after a workout you should eat a meal containing protein and complex carbohydrates.
Complex carbohydrates break down more slowly. You get them from fruit, vegetables and whole grains. They don’t usually cause the same sharp rise and fall. In practice this means steadier energy, fewer sudden hunger attacks and a better chance of keeping your daily eating under control.
The US Food and Drug Administration (FDA) uses the term carbohydrate quite broadly. The sugar alcohols mentioned in the original text are a good example: the name sounds like sugar, but they don’t affect insulin the same way as regular sugar. Just as important is the role of dietary fiber. Fiber fills the stomach and slows digestion without giving you a quick rush of energy.
How do you make insulin work for you?
Dr Atkin´s new diet revolution recommended eating more low-fat cheese, fish, chicken and eggs, but no more than 20 g of carbohydrates a day. This approach can work for weight loss for some people, but if you train, you also have to look at what the weight loss is coming from.
If fat goes down, great. If muscle goes down, the picture is worse. The original text says that with diets based on cutting fat, up to 50% of weight loss can come from muscle. That is not a result you want if you are trying to get stronger in the gym.
John Parillo’s recommendations here are practical and simple:
- Eat small portions often, consuming no more than 600 kcal at a time.
- Make sure every meal contains protein, a starchy vegetable or fruit, and dietary fiber.
- Consume each nutrient in an amount suited to your body type and goal. Someone who wants to build muscle mass should eat protein and carbohydrates at a 2:1 ratio; someone who wants to lose weight, at 1:1.
- Limit the fat you eat: it should make up about 10% of your daily calories.
So what actually happens? When blood sugar stays more even through the day, there are fewer situations where the body suddenly has to store a large amount of energy. Parillo also recommended leaving starchy carbohydrates out of the day’s last meal so that the body could burn more fat overnight while synthesizing glycogen.
Insulin in practice: the trainee’s menu
Honestly, most people don’t need to start with a complicated diet plan. Start with the plate. Put a protein source in every meal, add a slower carbohydrate and don’t forget the vegetables. That way you feel full, but the energy doesn’t arrive in one big wave.
Before a workout, choose food that doesn’t sit heavy in your stomach. After a workout it makes sense to eat protein and carbohydrates, because the muscles are more receptive then. That doesn’t mean you should go straight for sugar and pastries. Often an ordinary meal is enough: for example, chicken, rice and vegetables, or quark with fruit.
If your goal is to lose fat, watch your evening habits. The last meal of the day doesn’t have to be completely carbohydrate-free, but a large portion of starch right before bed can get in the way of weight loss for some people. If your goal is muscle mass, the picture is more flexible. Then total daily energy and protein intake matter too.
In the original text, Dr Bill Misner, Ph.D, warned that too much opposing pressure can break down muscle mass. It’s a good reminder: a diet that’s too strict, too much training and too little recovery won’t make your body better. Regrowing muscle is often harder than keeping it.
FAQ: insulin and glycogen
Does insulin always make you fat?
No. Insulin helps move energy into cells. You gain fat when your total daily energy intake stays higher than what your body burns over a long period.
Can you eat carbohydrates after a workout?
Yes. After a workout your muscles are more receptive, and a combination of protein and complex carbohydrates suits recovery well.
Is 20 g of carbohydrates a day right for everyone?
Not necessarily. Dr Atkins used it in the logic of his diet, but for someone who trains, the right amount depends on the goal, body weight, training load and recovery.
Training first! ArtGym
Author: Musclemag, translated by R Hunt
Source: WHO – physical activity.
