What’s all the fuss about low carbohydrate diets?


I have a keen interest in lifestyle medicine and the ways in which I can use modifications to the diet and exercise habits of my patients instead of medications to improve their health and wellbeing. In my practice people are frequently asking about how they can use diet and nutrition to improve their health and one particular area gaining increasing attention is the low carbohydrate diet.

Low carbohydrate diets are not new and take many forms. The idea of reducing carbohydrate intake was first popularised by William Banting, a British undertaker in the 19th century, and then again by the ‘Atkins Diet’ in the 1980s. More recently you may have heard reference to low carb, high fat (LCHF), ketogenic, paleo and caveman/carnivore diets.

What are carbohydrates?

To make things simple, I like to break dietary carbohydrates down into three broad groups:

  1. Green carbs: naturally occurring sugars and starches in fruits and vegetables.
  2. Beige carbs: Grain-based carbohydrates such as bread, rice, pasta, noodles, cereals and oats.
  3. White carbs: refined sugars added to sweets, cakes and confectionary as well as many processed foods/soft drinks.

What all carbohydrates have in common is that they are broken down by our bodies into glucose which is used for energy or stored for future energy needs. The reason I think it’s useful to divide carbohydrates in this way is that green carbohydrates (which contain fewer sugars and more fibre) are broken down more slowly and incompletely by the body causing a smaller rise in blood glucose levels. They also tend to contain other useful nutrients not found in beige or white carbohydrates.

Do we need carbohydrates?

This is a matter of some debate. The short answer is yes, carbohydrates can be a useful source of energy and I do not generally recommend zero carbohydrate diets to my patients. What is also true, however, is that many people are consuming more carbohydrates than their bodies need and I believe that for many years dietary guidelines in most countries have overstated the proportion of our intake which should come from these foods.

What are the consequences of carbohydrate excess?

Obesity is the most significant physical health problem facing us in the 21st century. It already affects 4 in 10 adults in the USA. The underlying health implications of obesity are many but the most important ones in relation to carbohydrate intake are type 2 diabetes, metabolic syndrome and non-alcoholic fatty liver disease. There appears to be a correlation with the increase in these conditions over the past 50 years and increasing carbohydrate intake across society. Eating carbohydrates raises our blood glucose level and so the body releases insulin in response. Over time we can become resistant to insulin resulting in weight gain and some of the issues listed above.

So should everyone be reducing their carbohydrate intake?

Maybe, but I try to tailor my recommendations to patients individually. The imperative for someone with type 2 diabetes or metabolic syndrome to reduce their intake is stronger than for a person without these conditions. There are various tests we can do to establish a person’s risk, from blood tests and heart scans, to continuous glucose monitoring with skin sensors to work out which carbs in particular do not work for you.

What should I eat instead?

The other macronutrients found in the human diet are fat and protein. Fat has long been demonized as unhealthy but it is actually filling and provides our bodies with a useful source of energy. Protein is found mainly in animal products: meat, fish and dairy. I recommend a diet similar to a typical Mediterranean diet based around whole, rather than processed foods and rich in fats (fish, olive oil, avocado, meat) and vegetables. I do not recommend low-fat dairy products or advise patients to avoid butter unless they want to. In terms of carbohydrate intake, I prefer this to be from vegetables and high fibre whole grains rather than refined or sugary foods. In some patients I use intermittent fasting techniques to boost the effects of carbohydrate reduction.

Achieving your lifestyle goals

Dietary intake needs to be tailored to your individual needs and preferences and takes into account other factors like exercise levels, family history and other medical conditions you may have. The most important factor of all is that any dietary changes need to be sustainable for you in the long term. There is no point struggling to adhere to a diet that you don’t enjoy as this will never last!

Dr Neil Forrest is a UK trained doctor based at IMC Camden. 

Call 6733 4440 to make an appointment. 

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