Getting to understand how your body functions is an important part of perfecting your diet. But when you’re doing your research, things have a tendency to get a little technical. Don’t worry! We’re here to explain the difference between digestion, synthesis, and metabolism so that you can understand how your body breaks down food and uses it for energy.
Digestion is the process your food goes through in your body. From mouth to toilet, your body works hard to break down your food, take out the usable parts, and discard the rest.
Digestion starts in the mouth, with the digestive enzymes found in your saliva. These enzymes, amylase and lipase, start working on the carbohydrates and fat in your food. When you swallow, the food is sent to your stomach, which uses acid to break down your foods even further. Next, your small intestine reduces the food particles in size and any useful nutrients are absorbed through the intestinal wall. Your large intestine then carries any waste matter to be discarded.
Carbohydrates are broken down into glucose which can be used by the body for energy. Imagine carbohydrates as long chains of glucose that the body separates – the longer the chain of carbohydrates, the longer it takes to digest, hence why health specialists try to get you to eat complex carbohydrates such as brown bread and brown rice as they will keep you fuller for longer and not cause any huge energy spikes.
Proteins are broken down into amino acids. These amino acids are what build tissue, hence why it is important to consume a moderate amount of protein when attempting to build muscle.
Fats are broken down into fatty acids which also help to form cellular structure and help absorb fat soluble vitamins. Diet pills help the body to speed up this fat burning process.
Your body then decides what to do with the nutrients it has gained – if it feels like you have been getting adequate nutrition recently, any excess glucose and fatty acids are stored in fat cells for later use.
It may surprise you to learn that the body doesn’t necessarily get all the nutrients it needs from food – it can actually synthesize some of its own from materials it has stored. Your body can create more nutrients and synthesize new cells and biomolecules.
For example, when there is a lack of glucose in your body, it starts to create ketones from fatty acids, which it can then use as energy. This is what the people on keto diets strive for – they don’t provide their bodies with enough carbohydrates to break down into glucose, thus forcing their bodies to start breaking down its fat supplies.
You may know that we get vitamin D by being exposed to the sun. Many people assume that the vitamin is soaked up through the skin, but actually sun exposure triggers a chemical reaction in the skin that converts cholesterol into the vitamin-containing cholecalciferol.
Processes such as these not only require the basic building materials gained from food, but also energy from nutrition. It is a common misconception how much energy is taken up by exercise compared to other functions – in fact normal body functions take up around 60-75% of your daily calorie expenditure. You could burn calories even if you were in a coma!
Different bodies need a different amount of calories in order to sustain normal functioning, otherwise they may not only start burning fat, but possibly even muscle as well.
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In scientific terms, metabolism refers to a number of biochemical processes your body uses to break down food as well as building components of cells. However, when people talk about metabolism in relation to weight gain or weight loss, they generally mean the rate at which your body burns calories.
More generally we can take metabolism to mean how much food your body needs in order to sustain itself – if you have a fast metabolism, your body uses more calories to keep the body functioning, while if you have a slow metabolism, your body doesn’t need as much, and any excess calories that are eaten will be stored as fat.
The bigger your body is, the higher your metabolism will be, as more food is needed to sustain it. Furthermore, the more muscly you are, the higher your metabolism is, as muscle requires more food to sustain itself than other tissues.
When people go on a crash diet, what they often find in the long run is that they end up gaining back the weight they lost, even a little more. This is because the body thinks that it is starving, and so slows down your metabolism, meaning that you become more efficient at using calories. You don’t just use your fat reserves for extra energy, you also use your muscle stores. This is why when dieting, you need to make sure you are either building muscle or maintaining a low-calorie diet.
Your body is an intricate machine that requires proper care in order to function correctly. Many people choose to take supplements to ensure that they are receiving proper nutrition, but the best solution is giving your body what it needs is with a balanced diet.
EHI Primary Care is run by Cathy, a 20-something fitness guru and yoga enthusiast. This is my blog, where I cover all sorts of topics around my healthy lifestyle.