The highs and the lows of the "Low Carb High Fat" diet.
Many people tend to subscribe to the famous "Low Carb High Fat" diet and others swear by it but a pertinent question to ask is whether these individuals do it well or if they are successful? Can the diet really improve diabetes control?
This week on Lifestyle Matters, Dr Ferghal and I take a deeper dive into the "Low Carb High Fat" diet".
Before insulin was discovered in the 1920s, a low carbohydrate diet was commonly prescribed to patients with diabetes. The logic was that the lower the carbohydrates consumed, the lower the glucose levels in our bodies. The prescription of this diet for diabetes control persisted despite the discovery of insulin! They were not wrong; there have been many studies demonstrating the efficacy of this diet in weight loss and reduction in insulin resistance. Insulin resistance is one of the underlying factors in the development of diabetes.
When we eat carbohydrates, these get broken down into sugar molecules which then triggers off insulin release for it to be taken up by our cells. If we have diabetes, insulin does not work very effectively, thus our glucose (sugar) levels rise. So, we can see why a low carbohydrate diet was prescribed for diabetes control.
However, long term studies have shown that this diet is not as sustainable as we may think it is. Further, their potential adverse effects from this diet which we will explore below.
Firstly, let us study the amount of energy we should obtain from various macronutrients.
As seen in the chart above, 45-65% of energy intake = 225-325gm of carbohydrate / day.
There are a few different types of low carb diets: • Very low: 20-50gm of carbs/ day (most effective, almost ketogenic) • Low: < 130gm / day • Moderate: < 230gm/ day
The reality is this; it is not easy to sustain a very low carbohydrate diet beyond 6-12 months. Many people fall back onto a low and moderate carbohydrate intake which does not produce results as effective as a very low carbohydrate diet. Further, people tend to increase their protein intake while on this diet which commonly is achieved through a higher meat intake i.e. saturated fat.
It is imperative to keep the saturated fat to < 10 % if one were to follow this diet. This is also extremely important for those who suffer with hypertriglyceridemia (where their triglycerides > 500 mg / dL ) as the ability to remove triglyceride enriched lipoproteins are saturated and can lead to pancreatitis. This shows the indirect effects of going on a low-carb diet.
There are other adverse outcomes from consuming a low carbohydrate diet over long term such as:
• Osteoporosis: Various mechanisms have been identified in rat models (watch this space!) • Deficiency in vitamins and minerals: Dietary fibre, Magnesium, Phytochemicals that are usually found in complex carbohydrates.
In summary, the key message from this is that if a low carbohydrate high fat diet suits one's lifestyle it is a reasonable choice as it certainly does demonstrate several benefits. However, due to issues with its sustainability and potential negative implications on our health, it may make it less than an ideal diet to stick to beyond a year.
Author: Dr Saveena Nithiananthan MBBS, FRACGP, IBLM
Savena is a General Practitioner, Medical Educator and member of the International Board of Lifestyle Medicine