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Pros and cons of a low carb, high fat, medium protein diet

Hadyn Luke posted this on Tuesday 13th of March 2018 Hadyn Luke 13/03/2018

Tags: Nutrition weight management

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Today’s blog looks at the pros and cons of a low carb, high fat, medium protein diet.

Dieting is a multi-million pound industry and everywhere you look there is different – and often contradictory – dietary advice. However, some personal trainers will hold qualifications relating to food and diet, such as a Level 3 Award in Prescribing Nutrition for Physical Activity or a Level 4 Certificate in Physical Activity and Weight Management for Obese and Diabetic Clients.

As some diets are nothing more than fads and others are potentially dangerous, your best approach is to follow evidence-based information and to consult a professional before embarking on any weight-loss programme.

What is considered low carb, high fat?

National guidelines consider low carbohydrate as being less than 40% of daily intake from carbs. A high fat diet is one above 35-40% calorie intake from fat.

What are the pros of a low carb, high fat, medium protein diet?

The weight of evidence shows that, when compared with a high carb, low fat diet, a low carb, high fat, medium protein diet will:

  • aid weight loss
  • preserve muscle mass
  • reduce hunger
  • reduce risk of diabetes, certain cancers and heart disease

This is achieved by lower glucose availability encouraging fat oxidation instead of fat storage.

Another benefit is that a low carbohydrate diet is likely to lower the concentration of blood insulin and improve insulin sensitivity. This can lead to clients diagnosed with Diabetes being able to reduce the amount of medication they are taking.

There is also the question of satiety – in other words, how full you feel after eating. Protein has the most effective and longest lasting effect; carbohydrate will make you feel full but the effects will be shorter lived; fat will make you feel full for longer than carbohydrate – indicating the benefit of this diet.

What are the cons of a low carb, high fat, medium protein diet?

There are, however, some potential downsides to this diet that need to be managed.

1. While you may feel you have reduced your carb intake, if you don't reduce them enough, or most of your carbs are coming from processed food, you may not see the results you want.

2. Conversely, if you cut the carbs down too far, it may affect your:

  • mood and cognitive functions
  • testosterone, thyroid and cortisol levels
  • immune system
  • energy levels and hydration

3. In extreme cases, it can cause ketosis, where the body has insufficient energy from carbohydrate so breaks down fat instead. Although ketosis is not always a bad thing, it wouldn't be advised to go from a 'normal' diet (a macro split of 50:30:20 carbs:fat:protein) straight into a keto diet - the reduction in carbs should be dropped slowly to assess your sensitivity. 

4. If a diet is high in meat and fish protein and low in fibre, this can cause inflammation from gut bacterial releasing TMAO (Trimethylamine N-oxide), which may lead to heart disease, colon cancer and diabetes.

5. The high fat element of the diet can also cause issues. Most people are aware there are “good” and “bad” fats and it’s important not to replace unhealthy sources of carbohydrate with processed products that are high in trans fats. Your protein and fat sources should still be 'natural' e.g. fresh / frozen / tinned fish, joints of meat, free range eggs, full fat dairy options. 


As with any diet, it’s important to stick to high-quality, preferably non-processed foods, and to take medical advice before you start your diet and if you notice any issues that concern you during your diet.

You will find following a low carb, high fat diet means you have to follow this advice. However, you will also find, following a high carb, low fat diet can also result in the same principle- eating high-quality, non-processed foods. Ultimately, any diet should not be a viewed as a short-term fix but as a lifestyle approach that is sustainable, healthy and safe. One thing that is a constant message is - eat high-quality, non-processed foods and adjust your calorie intake to dictate the goal outcome - weight gain or weight loss. 

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