PART 1: ARE CARBS MAKING YOU FAT?
Carbohydrates have come under a lot of abuse of the last few years and have even been claimed to be the cause of fat gain and obesity. But what are carbohydrates and are they bad for our health?
One of three macronutrients (protein, fat & carbs) carbohydrates come from plants… Plants make carbohydrates (sugar and starches) to store energy they get from the sun…. We, as humans, use carbohydrates to provide our body and brain with energy.
Types are carbs:
Sugar is the most simplistic form, monosaccharide (commonly referred to as “simple sugars”) due to their simple molecule structure and easiness of absorption. Examples are glucose and fructose.
Think: energy drinks & junk foods.
Glucose is the preferred fuel source for brain function and movement for our bodies.
Fructose on the other hand is metabolised in the liver and has a different metabolic pathway to glucose. This isn’t a preferred source of fuel for our bodies.
Starches are more complex (commonly referred to as “complex carbohydrates) due to the more complex molecule structure. This means there are digested at a slower rate and, in some cases, not at all.
Think: Vegetables and grains (fibrous foods)
Fibre is not completely broken down in digestion and passes through to the large intestines. Here it will play a few key roles:
- Provide food for the gut bacteria.
- Helps move food through the digestive tract and contributes to healthy bowel movements.
- Absorb water.
- Helps with fullness and prolonging satiety.
Digestion, metabolism and fat storage:
Digestion: Amylase is the enzyme found in saliva that is responsible for the initial breakdown of starches in to simple sugars. As they pass through the small intestines more enzymes join in to continue breaking down starches in to more usable energy, glucose and fructose.
Metabolism: As glucose is absorbed and enters the bloodstream, insulin is released to transport it through the body for either instant use or storage. In the case of usage, if we think of exercise, we will be using what’s available for our upcoming session… which is why consuming carbs 1-2hrs before training could enhance performance). What isn’t available will be drawn from our muscle storage.
Storage: What then isn’t used will be taken for storage. Ideally this will be taken to the muscle cells and stored as glycogen for a later date… It can also be stored in fat cells which is why carbs get such a bad rap. However, this is only going to happen if overall energy intake exceeds expenditure.
Glycogen is our stored fuel within the muscles cells, fuel we can use at a later date.
The more complex a carbohydrate the slower it’s digestion rate. Carbohydrates such as fibre are too complex to be digested and will therefore pass into the large intestine and be either excreted or consumed by gut bacteria.
Think of it this way: Imagine consuming a spoonful of pure sugar, it will be broken down and absorbed pretty quickly and used as energy or for storage. Now imagine consuming a potato (starch and fibre). The breakdown and digestion rate will be much slower.
Are they essential?
Carbohydrates is the only macronutrient that is not essential in the human diet. Should you choose to eliminate carbohydrates from your diet your body is capable of converting fatty acids into fuel through a process known as ketogenesis.
Instead of your body using carbohydrates (glucose) there is a switch in energy pathways to fat (ketones). Because of this process Ketogenic diets have become increasingly popular of late especially for weight/fat loss.
Should I just go keto?
Keep in mind that keto diets are nothing special. It’s just another way of creating a calorie deficit… Because your eliminating a food group (carbohydrates)
As with any diet it’ll work for as long as you adhere to it. Most diets fail because they are unsustainable due to their restrictiveness. In the case of keto, you are no longer “allowed” carbs… so say good but to:
bread, pizza, rice, potatoes, ice cream, pasta, oats, cereals, milk… and anything else that contains a high level of carbohydrates.
Carbohydrates come in two forms, sugar and starch. Both are broken down into glucoseand used as fuel for movement and brain function. The difference being sugars are quickly digested and absorbed due to their simplistic nature and starches are harder to break down due to their complex nature.
What doesn’t get used through daily living and exercise will be either stored as energy in the muscle cells (as glycogen) fat cell (as fat). The reason for fat storage will be based more on the fact total that energy intake is higher than energy output i.e. being in an energy surplus.
Remember that 1g of carbohydrate contains 4kcals. Compared to fat (9kcals) this is significantly lower.
Due to their quick absorption rate faster digesting carbohydrates could be beneficial for sport and training performance i.e. to be taken immediately before, during or after.
Due to their slower absorption rate and fibre content, slower digesting carbohydrates could be beneficial for longer sustained energy. Their nutritional profile will also offer a host of vitamins and mineral.
Although carbohydrates are not essential per se, they are our bodies preferred source of fuel. And although we are able to convert fat into usable energy it would come with the sacrifice of this food group which, when we consider energy balance, is not necessary.
In part 2 I’ll discuss the menstrual cycle and ask, is sugar actually addictive?