What is a low carb diet?

A low carbohydrate diet is a diet that limits all types of carbohydrates, also those found in grains, dairy, starchy vegetables, and fruits. There is no clear agreement on what defines a low carbohydrate diet. Based on consensus, a low carbohydrate diet contains less than 130 g of carbohydrate per day or constitutes between 10 and 26% of total daily energy intake. A low carb diet is not a ketogenic diet. Ketogenic diets are very low-carbohydrate diets that only contain 20 to 50 g of carbohydrate per day or less than 10% of total energy intake.  

What are the pros and cons of going on a low carb diet?

Pros

Low carbohydrate diets, like many other energy-controlled diets, may cause weight loss.  Initial weight loss during the first three months might be faster when compared to moderate and high carbohydrate diets but are similar thereafter.

A low carbohydrate diet may improve triglyceride and HDL cholesterol (good cholesterol) levels among overweight and obese individuals. There is often no effect on LDL (bad cholesterol) and total cholesterol levels unless carbohydrates were replaced by saturated fats.

Low carbohydrate diets can be helpful in improving blood sugar control in people with diabetes and insulin resistance in the short term, and short term (less than 6 months) reduction of HbA1C is bigger when compared to higher carbohydrate diets, but there is less difference after 1 year. Low carb diets can reduce the amount of blood glucose lowering medication or insulin that a person with diabetes requires.

People following a low carb diet report that is has an appetite lowering effect which can help to improve compliance to the diet.  

Cons

Low carbohydrate diets can easily be too low in fiber and could have a negative effect on your gut microbiome and digestive health if not carefully applied with the help of a registered dietitian. Fermentation by-products of fibre such as short-chain fatty acids, phenolic compounds and certain gut bacteria like bifidobacteria are healthy and protective for the large intestine and potentially help lower the risk of colon cancer, but more research is required on whether a low carb diet increase the risk for colorectal cancer in the general population. Studies however do show that short term use of a low carbohydrate diet (four to eight weeks) has a negative effect on colonic health of obese and overweight individuals.

A low carb diet can be low in certain vitamins and minerals and increases the risk for deficiencies; but this depends on the nutrient density of the food choices someone makes. A dietitian can help to optimize your low carbohydrate diet for maximum nutritional quality.

Some individuals with certain genetic factors might experience an increase in LDL cholesterol (bad cholesterol) when following a low carbohydrate diet so it is better to have your lipid profile assessed before you start a low carbohydrate diet, especially if you have a genetic risk.

A low carbohydrate diet is often not sustainable and long-term compliance is low. 

Low carbohydrate diets might cause low blood sugar or hypoglycaemia in people with diabetes, and people with diabetes must be medically supervised when choosing to follow a low carb diet.

Long-term low carbohydrate diets increase the risk of cardiovascular and cancer mortality. Carbohydrate restriction for weight loss should be limited to short periods (2–6 months) followed by a transition to a healthy dietary pattern for the long-term with adequate intake of fiber-rich carbohydrate foods and inclusion of plant-based proteins and unsaturated fats to ensure nutritional adequacy and promote overall- and cardiovascular health.

Our verdict

The best way to lose weight, is through making sustainable changes to your lifestyle for the long-run; changes you can easily stick to without being overly restrictive. This method requires a mindful approach and less of a diet approach. But not everyone is patient and happy with a gradual approach. So, for those who prefer a ‘diet’ approach, a low carbohydrate diet can be an option as long as it is used for a period of 2 – 6 months only, whereafter one should transition towards including enough high fiber carbohydrate foods like grains and fruit as part of a balanced diet. A low carb diet must be supervised by a dietitian to ensure it is nutritionally adequate and safe for those with medical conditions such as diabetes and cardiovascular disease.