Low carb vs low fat: which is better for weight loss according to a nutritionist

One question I often get from clients is which diet is best for weight loss? Is it low carb or low fat?

While both diets can achieve weight loss, the two are very different and have different nutritional benefits and weight loss outcomes overall. 

What is the low carb diet?

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Low carb diets have varying amounts of carbohydrates. The ketogenic diet for example means that you consume only 50-30g of carbs per day meaning you are cutting out most carbohydrates from your diet completely. A typical day usually consists of protein and only some fruit or vegetables allowed such as berries, pumpkin, avocado and cauliflower. 

A general low carb diet allows up to 130g of carbohydrates a day allowing you to follow a less restrictive diet and feature some non-starchy vegetables, legumes and low GI grains. 

Generally on low carb diets you eliminate white bread, pasta, sweets and high starch vegetables and fruit.  

What is the low fat diet?

Low fat diets include reducing your fat intake to just 30 per cent of your calorie intake. 

Foods high in fat such as avocado, butter, full fat dairy, whole eggs and nuts and seeds are generally avoided. 

Instead, on a low fat diet you tend to consume lean meat such as skinless poultry, low fat dairy, legumes and egg whites. 

Which diet is better for weight loss?

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In my clinic, I often advise clients to start on a low carb diet for weight loss. Research indicates that low carb diets on a short term basis are more effective. 

One 12-week study also found that adolescents on a low carb diet lost an average of nine kilos as opposed to 4kg on a low fat diet.

And another study looked at the weightloss of 322 people on a low carb, low fat and Mediterranean diet over two years. 

Over 17 people on the low carb diet lost more weight than the low fat diet over 12 months, but over two years, the results between the diets yielded similar results. 

That said, from a nutritional perspective, I would recommend low carb over low fat as cutting out fat from dairy often results in more processing and a less healthy food overall. 

Which diet is better for fat loss?

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You might assume that a low fat diet would mean a better outcome for fat loss, yet a small study showed that those following a low carb diet had more fat loss. 

What's more, several studies have shown that low carb diets result in lower belly fat than those following a low fat diet. 

Which diet is better for satiety?

When looking at which diet produces more feelings of fullness and satiety and curbing hunger overall, the low carb diet came up trumps in one study. 

High protein diets, such as the low carb diet, tend to promote feelings of fullness and decrease the hunger hormone ghrelin.

Which diet is better for blood sugar levels?

For reducing blood sugar levels, the low carb diet has shown many benefits. One study showed that the low carb diet was better for reducing blood sugar levels, weight loss and insulin needs than a low fat diet. 

Another larger study with diabetic people also produced similar benefits for those on a low carb diet in contrast to a low fat diet. 

Which is better for your health overall?

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Over various studies, the low carb diet has yielded better results for cholesterol, blood pressure and insulin levels, however when looking at very low carb diets such as the ketogenic diet, the variance of plants and fibre is less, therefore not as beneficial for gut health. 

With my clients when recommending a low carb diet for weight loss, I still suggest that after three months, they reintroduce starchy vegetables and fruit as well as legumes. 

Overall, a healthy balanced diet means you are consuming at least 25-30g of fibre a day which is very hard to achieve on a low carb diet such as keto.