Carbohydrates
A macronutrient covering sugars, starches and fibre, the body's main source of energy, where quality (simple vs complex) matters more than raw quantity.
Carbohydrates provide the body’s main energy (4 kcal/g). They are classed as:
- Simple sugars (monosaccharides, disaccharides): glucose, fructose, sucrose, lactose, absorbed quickly
- Complex carbohydrates: starch, absorbed more slowly
- Fibre: indigestible carbohydrates, good for the microbiome
The original angle (neither essential, nor to be demonised): a key debate: carbohydrates are the only macronutrient that is not « essential » in the strict sense (the body can make vital glucose through gluconeogenesis from protein and fat). This fuels low-carb and keto diets.
BUT that does not mean they are « bad » or useless:
- They are the preferred fuel of the brain and of intense effort
- Many carbohydrate foods (vegetables, fruit, pulses, wholegrain cereals) are packages of valuable fibre, vitamins, minerals and polyphenols
- Cutting them out completely can harm the microbiome (less fermentable fibre)
The real issue: QUALITY, not raw quantity. Compare:
- « Empty » carbohydrates: sugar, fizzy drinks, white flour, ultra-processed foods → blood sugar spikes, few nutrients → limit
- « Full » carbohydrates: vegetables, whole fruit, pulses, wholegrain cereals, cooked-and-cooled starchy foods → fibre, micronutrients, slow absorption → beneficial
Lumping together the sugar in a fizzy drink and the carbohydrates in a lentil is a common mistake.
Moderating the glycaemic impact:
- Favour complex, fibre-rich carbohydrates
- Combine them with protein, fibre and fat (a complete meal)
- The order of foods (vegetables and protein before starchy foods) reduces the spike
- Cooking and cooling (resistant starch) lowers the GI
Carbohydrate needs depend heavily on activity: an endurance athlete needs a lot, a sedentary person less.