Carbohydrates fall into two main categories, referred to as simple and complex carbohydrates, which reflect their molecular structure. Both simple and complex carbohydrates consist of chains of sugar molecules, but the chains are much shorter in the case of simple carbohydrates, consisting of just one or two molecules: these are known as monosaccharides and disaccharides respectively. The most common monosaccharides found in food are fructose, galactose, and glucose, whilst the most common disaccharides are lactose, maltose and sucrose. Complex carbohydrates (known as polysaccharides) can consist of much longer molecular chains. Most fruits and vegetables contain both simple and complex carbohydrates.

Due to their very basic structure, simple carbohydrates are absorbed and digested quickly, which can provide a fast and short-lived spike in energy, followed by a drop. Overconsumption of simple carbohydrates can lead to weight gain in the form of fat, and chronic overconsumption can sometimes give rise to obesity, type 2 diabetes, and heart disease. Because simple carbohydrates lack fibre, they can be consumed in larger quantities without leading to a feeling of fullness, and so can carry a risk of overeating.

The other 9 amino acids can’t be produced by our bodies and so we need to get them from the foods we eat; they are known as the essential amino acids, and their names are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Each of these amino acids performs a specific role in helping to maintain our health. For example, histidine and lysine can support our immune function, threonine helps to maintain skin quality and prevent bleeding, and tryptophan contributes to the production of serotonin, a neurotransmitter that helps regulate our mood and appetite.