Calories and what food really does to your body
A calorie is a convenient number, but your body doesn’t read food like a calculator. The same amount of energy can feel very different depending on whether your plate holds a sugary bun, fish, eggs, porridge or a proper dinner.
The simple truth: a calorie helps measure energy, but it doesn’t show the whole picture. What also matters is how food affects blood sugar, insulin, glucagon, hunger, recovery and fat stores.
Why calories alone don’t explain nutrition
Once scientists realized that the energy in food can be measured, a unit was created for it: the calorie. After that, the conversation became simple. A gram of fat contains 9 kcal, while a gram of carbohydrate or protein contains 4 kcal. This quickly led to the idea that fat is bad and carbohydrate is good energy.
The body is more complicated, though. It doesn’t know what a calorie is, and it doesn’t sit at the dinner table adding up numbers. Your body responds to different nutrients in different ways. One food raises blood sugar quickly, another more slowly. One keeps you full for longer, another triggers a new craving an hour later.
That’s why the question isn’t only how much energy a food provides. What happens after you eat matters just as much: how quickly the food is absorbed, which hormones kick in, and whether the energy reaches your muscles or goes into storage.
How do calories, blood sugar and hormones work?
Carbohydrates are broken down into glucose in the body. We usually call this blood sugar. When sugar reaches the blood, the pancreas releases insulin. Insulin’s job is to clear excess sugar from the blood and store the energy where it can be used.
When a lot of carbohydrates arrive at once and are absorbed quickly, blood sugar spikes. More insulin is then released, too. Sometimes blood sugar then drops too low. The result is familiar: fatigue, hunger, sweet cravings and a feeling that you want to eat something more.
Protein works differently. Protein is made up of amino acids, which are the body’s building material. High-quality protein contains all the essential amino acids, which the body can’t produce itself. There are eight of them in total; for growing children, arginine and histidine are important too. Animal protein is usually complete, while plant protein often needs to be combined.
When you eat protein, the body releases glucagon. It acts in the opposite way to insulin: it helps unlock energy stores so that fatty acids become available to your muscles and glucose to your brain.
Fat stays fairly neutral in this sugar war. It doesn’t directly raise insulin or glucagon, but it slows the absorption of both carbohydrates and protein. Fat also helps fat-soluble vitamins and calcium to be absorbed, and it plays a part in building cell membranes and some hormones. Omega-3 fatty acids, which you get from fish, support the balance of eicosanoid hormones.
Calories and stable blood sugar in practice
There must always be a certain amount of glucose in the blood, because the brain needs it for energy. If there’s too little sugar, weakness sets in and concentrating becomes hard. If there’s too much, the body has to correct it quickly.
High blood sugar isn’t a concern only for people with diabetes. The more sugar there is in the blood, the more insulin may be needed. If there’s room in the muscles and liver, glucose is stored there as glycogen. Once those stores are full, the excess is converted into fat and stored in fat cells. Those stores don’t “fill up” nearly as easily.
From a training perspective, circulation and recovery matter too. If the body constantly has to deal with big swings in blood sugar, your muscles may not get oxygen and nutrients in the best possible way. In the evening before bed, it makes no sense to raise insulin levels for no reason, because the night is an important time for recovery. The exception is an evening workout, after which you should still eat carbohydrates.
In 2004, the recommendations on fat were changed. For carbohydrates, too, the discussion has moved on, because high blood sugar and insulin resistance often go together. When your cells take up sugar well, insulin sensitivity is better and your muscles can use nutrients more efficiently.
Blood sugar that’s too low isn’t a goal either. The body may then release more glucagon, cortisol and adrenaline. The last two can start breaking down muscle protein to make glucose for the brain. A poorly planned diet can lead to a situation where both your form and how you feel suffer.
What does a calorie on your plate really mean?
The best results usually come from mixed meals. When a single meal contains a sensible amount of carbohydrates, protein and fat, insulin and glucagon don’t rise more than necessary. You stay full for longer and your energy is steadier.
Good carbohydrates are absorbed more slowly and provide dietary fiber and micronutrients in addition to energy. Poorer choices raise blood sugar quickly but add little of value. Honestly, the difference is quite noticeable: one lunch keeps you working through the afternoon, while another sends you looking for coffee and sweets two hours later.
Official guidelines recommend eating 50% carbohydrates and 15% protein. For some people, though, that ratio can push blood sugar too high, even when the carbohydrates come from good sources. The Atkins diet recommends less than 10% carbohydrates and more than 30% protein, but that can drive blood sugar too low.
The answer lies somewhere in between. If you train a lot and burn a lot of energy, you may need more carbohydrates. On a quiet day, the body needs less fast energy. A rough starting point could be 40% carbohydrates and 30% protein, but the right ratio depends on your body, your training load and your goal.
FAQ
So is the calorie completely pointless?
No. A calorie shows the energy in food and helps you estimate amounts. It just isn’t enough on its own, because the body responds differently to protein, fat and carbohydrate.
Does fat always make you fat?
No. Fat does provide a lot of energy, 9 kcal per gram, but it performs important functions in the body. The problem arises when total energy intake and the ratio of nutrients get out of balance.
Should you avoid carbohydrates?
No. Carbohydrates are needed especially when the physical training load is heavy and during recovery. The difference lies in the source, the amount and the timing.
Translated from Body magazine, author: Jukka Harju
Author: Greta
Source: ARMUDU
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