Low-carb diets: are they right for you?

Even if you haven’t tried a low-carb eating plan, you’re probably familiar with the concept of cutting bread, pasta, and potatoes, for weight loss and/or to lower blood sugar. Carbs are often cast as the popular villain in diet culture, and used as a catch-all term for any unhealthy-but-delicious fare you might want to indulge in.

Although a low-carb diet can be effective, it’s not a magic bullet - and carbs as a category aren’t necessarily always the enemy. But because of the diet industry’s tendency to demonise the whole group, all carbs typically get lumped in together.

What is a carb?

A carbohydrate is one of three essential macronutrients and forms a large part of our diet, the others being fat and protein.

Carbohydrates are important for our health as they help boost energy levels, as the body and brain’s main source of energy. They also help prevent against disease, as vegetables such as pulses and varieties of starchy food, such as potatoes, maintain good gut and bowel health.

Cutting carbohydrates from your diet can put you at increased risk of a deficiency in certain nutrients. For example, if you take away foods like pasta or fruit, you’re lowering your fibre, vitamin and mineral intake, unless you're able to make up for the nutritional shortfall with healthy alternatives.

Carbohydrates are broken down into glucose (sugar) before being absorbed into your blood. The glucose then enters your body's cells with the help of insulin. Glucose is then used by your body to fuel your activities, whether that's going for a run or simply breathing. Unused glucose can be converted to glycogen, which is found in the liver and muscles. If more glucose is consumed than can be stored as glycogen, it's converted to fat for long-term storage of energy.

How many carbs should I be eating?

Here in the UK, the NHS recommends people aim for an average of around 260 grams of carbohydrate per day. In the US, that figure is between 225 - 325 grams. But before you take those numbers and run, it’s important to consider your unique physique and goals.

By first calculating your Basal Metabolic Rate (BMR), you’ll know exactly how many calories you need to be consuming to maintain your current weight, and therefore how many you need to consume if you want to lose a few pounds (or gain some). Then you can work out how many carbs you should be eating.

The NHS suggests that roughly 50% of your daily calorie intake should come from carbohydrates - so if your BMR says you should be consuming, let’s say 1800 calories, around 900 calories should be from carbs, which is 225 grams (carbohydrates provide 4 calories per gram, as do proteins).

Low-carb eating patterns typically limit carbs to around 25% of your daily calorie intake (roughly half of the recommended amount). So in the example above, a low-carb eating plan would mean 450 calories from carbs, which is around 112 grams.

Types of low-carb plans

Whilst there are no end to different brands and methods of low-carb diets, they essentially fall into one of two broad types: those that lower carbs and raise fat, and those that lower carbs and raise protein.

Low-carb, high fat diets, such as the keto diet, focus on fat-rich foods that can serve as an alternate fuel once your body uses up your curtailed number of carbohydrates. A typical breakdown for 2,000 calories per day on a keto plan would be 70–80% fat, 5-10% carbohydrate, and 10-20% protein, or around 165 grams fat, 40 grams carbohydrates, and 75 grams protein. But as we saw above, those numbers are going to vary from person to person.

Diets with fewer carbs and more protein typically bump your protein percentage up beyond the NHS recommendation of around 50g of your daily calorie intake. The amount you aim for will depend on the plan you follow but roughly speaking low carb, high protein diets will recommend that you get 30% to 50% of your total calories from protein, which for 2,000 calories per day would mean 700 - 1000 calories from protein (which is between 175 to 250 grams). Again, the exact numbers will vary.

Note: Please make sure you talk to your doctor before dramatically altering your eating patterns to be sure you’re meeting your nutritional needs.