Can very low calorie diets cure diabetes?


Reversing diabetes using a very low calorie diet (VLCD) has been a big topic in the media recently following the publication of a study on the subject in the scientific journal Diabetes Care. The official treatment for diabetes recommended in the UK by the National Institute for Health and Care Excellence does not include advice to try a VLCD. However overweight people with type 2 Diabetes are strongly advised to lose weight. New research is always exciting but it’s important to think about what the results actually tell us, to consider them in the context of existing knowledge and to think about what we know about the long-term effects of any proposed treatment. So can very low calorie diets cure diabetes?

The research that has caused all the excitement relates to type 2 diabetes. This is the type that people tend to get when they are adults and it is often associated with being overweight. You must not try a VLCD if you have type 1 diabetes which has to be managed with insulin injections or if you have type 2 diabetes and you are on medication which lowers your blood sugars. A very wide range of medications are now used in the management of diabetes. It is important that you speak to your doctor to understand your medication fully and then talk to your dietitian about what this means for your diet

The people who took part in the study responded to an advert and so were likely to be well motivated. This is important because the research does not tell us whether a randomly selected group of people with different levels of motivation would have responded in the same way. Furthermore there was no control group so we do not know how the results would compare for a group of people with similar characteristics given more traditional dietary advice.

The study was carried out in 2 stages. The first stage involved the participants following a diet of meal replacement shakes plus non-starchy vegetables (eg lettuce, cucumber, kale, spinach and cabbage.) This kept their calorie intake down between 624 and 700 calories/day for 8 weeks. This is a pretty big ask and not without risk. You should never follow a diet of this type without supervision from a doctor or dietitian as it’s important to ensure that the composition of the VLCD provides everything your body requires to keep functioning. It’s also essential to be closely monitored. VLCDs can cause extreme fatigue, uncomfortable constipation and loss of lean muscle mass, which can impact mobility and the health of the heart and lungs. Gallstones are another common complication and although these may disappear once a more normal diet is resumed they can become a painful long-term problem. There are also reported cases of sudden death in people on extreme, unmonitored VLCDs so please get proper professional advice.

After the VLCD stage the participants followed a strictly controlled weight loss diet for 6 months. This diet kept their calorie intake below the level of the calories they used up in their day to day activities. Again this is not easy. Sticking to a diet for 6 months requires discipline and commitment.

The study was very small with just 30 participants. After 8 weeks on the VLCD, 12 of the 30 participants had blood glucose levels that indicated that they no longer had diabetes. This was still the case for these same 12 people after the 6 month weight loss diet. These people referred to by the research team as “responders,” tended to be younger (average age 52 as compared to average age 60 in non-responders) and tended to have had their diabetes for less time (average 3.8 years compared to 9.8 years in the non-responders.)

So what are the facts that we know following this research?

Can very low calorie diets cure diabetes? Fact one

Under ideal conditions with intensive support from professionals, 40% of a very small group of highly motivated people with type 2 diabetes were able to become free of the disease following 8 weeks on a VLCD below 700 calories a day.

Can very low calorie diets cure diabetes? Fact two

After a further 6 months on a strict weight loss diet again with intensive professional support these same people remained free of the disease.

We don’t know what will happen once these people have been back on a weight maintenance diet for a few years. For example they may go back to old habits and their diabetes might return. The researchers suggest that they think there is a “personal fat threshold” above which fat is deposited in the liver and pancreas, where it causes damage and can prevent the pancreas producing insulin properly. This is certainly interesting and warrants further research. Scientists need to do larger scale studies where randomly selected participants are randomly assigned to either follow the VLCD approach or a more traditional approach. Those who become free of diabetes should then be followed up over an extended period to see what happens.

In the meantime if you are overweight and have type 2 diabetes, losing weight is hugely important. How you do this will depend on your lifestyle, medication and food likes/dislikes, so it’s important that you see a Dietitian and get yourself on the right track.

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