Carbohydrate

Groombridge Place, June 2013

After much deliberation, I decided to call the talk I gave at the weekend 'Carbohydrate'. It was part of a scheduled day of talks from healthcare professionals at a public awareness day organised by the local Diabetes UK voluntary group. Other speakers included doctors, podiatrists, eye specialists and a paediatric dietitian who was planning to talk about exercise (unfortunately I missed most of her talk because I was talking to someone about injection sites).

A colleague had sent me a presentation that she had recently delivered, so I based mine on hers and stole her case study. I started by reminding people that all types of Diabetes are characterised by blood glucose that is higher than it should be, and that the source of glucose in the blood is carbohydrate from the food we eat. As a Dietitian specialising in Diabetes, carbohydrate in food is my bread and butter (not so much butter, actually), and then posed the question: how do I decide what advice to give to patients about what they should eat?

This brought us on to the evidence-based nutritional guidelines published by Diabetes UK in 2011, and the changes that this document brought to the accepted picture of healthy eating for Diabetes. The trouble with the scientific method is that as more evidence is accumulated and new guidelines are researched and published, our total knowledge increases and conclusions can change from one day to the next.

The new guidelines advise that the primary nutritional strategy in Type 2 Diabetes should be weight loss above all else, and what's more, that there is no evidence to favour any one approach to weight loss over any other. Limiting energy intake overall is more important than where the calories come from. The document also says that low carbohydrate diets can be particularly effective at producing improved blood glucose control, especially when weight loss is achieved.

This is a drastic U-turn. Previously, guidelines suggested that a significant proportion of food eaten should be starchy carbohydrate - 50% or more of the total dietary intake. The potential consequences of restricting carbohydrate were perceived as deficiency of B vitamins, and increased fat intake leading to weight gain, higher blood cholesterol and an increased risk of cardiovascular disease. From one day to the next, our advice based on the best evidence goes from recommending fairly high carbohydrate portions to weight loss at all costs with a definite option of low carb. No wonder people are frustrated by reporting in the popular press, where advice seems to change every time a journalist sneezes.

One of my colleagues has thoroughly researched the low carb approach, and even converted her own diet to exclude carbs. She has converted the other Diabetes staff to the new low carb religion, and pioneered this method with her patients. We have two treatment groups increasing in numbers every month - a 'reducing carbs' cohort, and a 'very low carb' group.

'Reducing carbs' means limiting carbohydrate intake to 120g or less a day - 30g per meal and 30g for snacks. As an example, a slice of bread from a medium sliced loaf is 15g carbohydrate, as is a diet yogurt, or a portion of fruit. 30g carbohydrate equates to three tablespoons of cooked rice or pasta, or three egg-sized potatoes. Admittedly it usually involves a change in diet, but not necessarily a drastic change, and most people would find it manageable with a bit of forward planning.

'Very low carb' or VLC is a different kettle of fish, and this plan limits carbohydrate to just 40g or less per day. This means giving up all starchy carbohydrate - no bread, pasta, rice, cereal, potatoes or other starchy vegetables, with allowed carbs limited to a small amount of milk, berries and pulses and natural yogurt. Animal and vegetable protein features heavily, including nuts and seeds, along with less carb-heavy vegetables and salads. Saturated fats should be replaced with unsaturated as much as possible, and caffeine and artificial sweeteners should also be avoided.

The idea of both these diets is that the less carbohydrate you eat, the less glucose ends up in the blood. Consumption of lower calorie foods also increases, including vegetables and salad, so a very welcome by-product is weight loss. The VLC diet is also intended to change the body's metabolism from using carbohydrate to using fat as the main fuel for energy, which was once assumed to be a bad idea. It has now been shown not to have the undesirable effects that were once thought likely in the short term, although we still don't know the long-term consequences. Another very positive aspect of the change to fat metabolism is that it seems to have an appetite-suppressing effect.

For people with Type 2 Diabetes who are overweight, a VLC plan can bring about a miraculous transformation. High blood glucose levels start to drop straight away; medication can be reduced, appetite is reduced and weight starts to decrease. This allows medication to be reduced further, success reinforces motivation, and some people have even stopped taking the majority of their Diabetes medication, including insulin.

This is not to say it works for everyone. There are some who can't manage to construct an acceptable daily meal plan without carbohydrate, and others unable to tolerate the change to fat metabolism, which can result in headaches, constipation and fatigue over a transition period. Increasing emphasis on protein and vegetables can prove too expensive, although it is to be hoped that the reduction in total amount of food needed can offset the expense up to a point. Family circumstances are often the biggest barrier - it is not a suitable plan for children, other adults may not want to join in, and making separate meals can be impractical. I've thought about it for a while, and I'm not sure that I would be able to deal with the practicalities of this VLC option.

In between talking about the nutrition guidelines and explaining our low carb diets, I managed to include some audience participation, in the form of 'Find the Carbs'. I showed a selection of pictures of meals, and got people to tell me which components contained carbs, to illustrate how an acceptable diet might contain less carbohydrate than the traditional choices of toast, jam, cereal, fruit, yogurt and juice.

My talk seemed to go down well, and the whole event was very well attended. I met some more local Dietitians, which is always good to do, and the Diabetes UK local group committee and members actually talked to me a bit for a change. I still think I might not go to any more of their weird meetings, though.