Should you opt for a LCHF diet?
The low carb high fat (LCHF) diet has been heralded as a weight-loss sensation, but is it advisable for Type 1 diabetes?
The Government's healthy eating advice recommends just over a third of your diet should be starchy foods – whole grains, potatoes and bread, rice and pasta (choose wholemeal), and another third should be fruit and vegetables: this accounts for more than half your intake. Everyone with diabetes needs some carbohydrate, and it’s important for people with Type 1 diabetes to understand which foods are sources of carbohydrate (see right), how to estimate carbohydrate portions and how to monitor their effect on blood glucose levels.
What does the evidence say?
Adults are recommended to eat an average of 260g of carbohydrate per day (NHS, 2016). So should people with Type 1 diabetes ignore this advice and go low carb by embracing LCHF eating? Although there have been lots of studies supporting the use of such diets in Type 2 diabetes, more quality research is needed before you can be sure that this diet is beneficial to blood glucose control in Type 1 diabetes. Current research and guidelines from Diabetes UK (Diabetes UK, 2011) support recommendations that people with Type 1 diabetes restrict saturated fat intake, which is in keeping with recommendations on fat from the Eatwell Guide.
The case for LCHF
There is a wealth of research on LCHF diets in people with Type 2 diabetes and this way of eating has been shown to be effective in reducing blood glucose (Nutrition and Metabolism, December 2005; Nutrition and Metabolism, December 2008). The X-PERT Health programme supports a LCHF diet approach for Type 2 diabetes (Xpert Health, 2015).
Most people with Type 2 diabetes also need to manage their weight; there is some evidence that LCHF eating may lead to quicker weight loss as well as keeping it off (New England Journal of Medicine magazine, 2008). Such studies help evaluate how different ways of eating may be beneficial to people with diabetes, and is crucial in helping dietary recommendations to evolve over time.
The case against LCHF
It has been argued that eating fewer carbs, and getting more calories from fat could be undesirable (Journal of Nutrition and Dietetics, Vol 4, 1990). There have also been concerns that a diet low in carbohydrate will be lacking in certain nutrients and that a high saturated fat intake can increase risks of heart disease (Diabetes, Vol 58, 2009). Even authors of the study that showed that weight loss was quicker in people on a low-carb diet suggest that their findings should be interpreted with caution, and that we need more research on how such diets may affect risks of heart disease (New England Journal of Medicine, May 2003).
Studies have supported the use of low carbohydrate diets in Type 2 diabetes, but there’s little evidence in Type 1, where diets higher in fat and saturated fat and lower in carbohydrate have been associated with higher HbA1c levels and worse glycemic control (American Journal of Clinical Nutrition, February 2009).
The amount of carbohydrate you eat should depend on your individual goals and this is best discussed with your dietitian and diabetes team. It’s important to get to a stage where you can self-manage your diabetes and learn to accurately match your carbohydrate intake to insulin, regardless of how much carbs you eat.
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