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As humans progress and our knowledge surpasses those of generations before us, one would expect us to have something as simple as weight-loss down pat. Unfortunately, this is not the case. On the contrary, the more information we are subjected to, the more confusing it seems to get. Do we cut out sugar completely? Are we allowed to eat saturated fat? Should we be lobbing our 3-fat star mince down a well? In amongst all of this chatter, one of the most common queries I see is whether low-carb diets work for fat loss. Are they the secret to weightless?

In our obesogenic world, morbidity and mortality rates relating to our unhealthy lifestyles continue to climb. Most of us still list weight-loss as one of our main new years resolutions. Personal trainers, nutritionists and online coaches continue to be in high demand despite the ostensibly saturated market. Some of those who have successful lost weight attribute it to their reduction in carbohydrates consumption.

The ketogenic or “keto” diet is one example of a popular diet that focusses on carb-reduction. Those who adhere to this approach replace most of their carbohydrates with fat in order to promote fat-burning for energy. Whilst there are many examples of people who commit to the keto diet who successfully lose body-fat, the original intention of the diet was not for the general population. Rather, the keto diet is used in a clinical setting to manage specific health conditions, such as epilepsy. It may seem peculiar that a diet utilised in a regulated health setting is being promoted for the general population who simply want to lose body fat.

Our body utilises three macronutrients for daily functioning: carbohydrates, fat and protein. Each source of fuel has specific functions for the body. Among many other roles, protein is essential for cell growth, repair and function, and is required for building muscle and maintaining good immune health. Carbohydrates are our body’s main source of fuel, and they help control blood glucose and insulin metabolism in the body. Fat is needed to protect our vital organs and to absorb important micronutrients that are only fat-soluble. It is also utilised as a source of energy, and for the production of hormones.

The premise of low-carb diets centres on the type of fuel source the body relies upon for energy. In a standard diet, our body will use carbohydrates as its main source of fuel. Since the ketogenic diet heavily reduces carbohydrate-intake and instead focusses on fat-intake, this means that the body is burning fat as it’s main source of energy, instead of carbohydrates. People equate the increase of fat breakdown to a decrease in body fat.

As with any diet, you will only ever lose body fat if you are eating less calories than your body requires for energy. It does not matter what source of energy your body uses, if you are eating 2000 calories of fat and protein, but your total daily energy expenditure is less than this, you simply will not be losing weight. Those who adopt a keto diet are simply creating a calorie deficit, the same way in which any other diet will lead to fat loss.

Does that mean it’s case-closed for low-carb diets?

Not necessarily. Just because they aren’t a magical weight-loss tool, does not mean that some people don’t use them as an effective tool. Foods high in carbohydrates are often high in calories; highly palatable; and easy to consume in large quantities. High-carb foods often aren’t as satiating as their high-protein counterparts, and therefore it can be difficult to keep cravings at bay. Moreover, some people experience energy and concentration slumps after ingesting a big meal with a lot of carbohydrates.

As with many things in the health and fitness industry, mindset is key. If you think you are going to lose body fat by following a keto diet, and believe your hunger levels are reduced which in turn makes you eat less – you will likely achieve your fat loss goals. The expectation effect is a significant driver of behaviour – how you anticipate the efficacy of something will often impact the objective efficacy of it. You think it will work, so it will.

On the other hand, if you’re energy-depleted and feeling bereft without your delicious and satiating carbohydrates, there’s no need for you to be miserable and adhere to a low-carb diet. If you look at the fact of the matter, it’s the reduction in energy-consumption that causes weight-loss. You need to work out the most effective and healthy way you can achieve that energy-deficit. For some people, this is incorporating a low-carb diet – but for many people, there’s significantly better options. Moreover, there is a risk that you are missing out on essential vitamins and micronutrients by limiting foods high in carbohydrates.