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Fresh Living Network

The low carb diet debate

Current rating: 3 from 3 votes.
Sweet Life magazine gathered readers' questions and asked Prof Tim Noakes how the high fat diet affects diabetics.

They also got their dietician, Genevieve Jardine, and endocrinologist, Dr Joel Dave, to weigh in...

What exactly is this diet?

Tim Noakes: A low carbohydrate, moderate protein, high fat diet. This diet is most effective for people with diabetes – either Type 1 or Type 2, or pre-diabetes, like me. It also helps treat obesity, but it’s obviously not the diet for everyone. The question is whether it’s for 10% of the population, or 90% of the population – I think it’s about 60% or more.

Low carb means no bread, pasta, cereals, grains, potatoes, rice, sweets and confectionery, baked goods. You have to be resolute – and the more severely affected you are, the more resolute you have to be. If you’re already diabetic, you have every reason not to eat these foods. 

Genevive Jardine: The low carb diet has come and gone out of fashion over the decades, and Prof. Noakes has based his position on personal experience that he claims has worked for him. There are a few different diets that have a positive impact on reducing weight and improving blood glucose levels. Confusion comes in when we try to adopt a ‘one size fits all’ mentality in approaching something as multifaceted as diet and diabetes.

Joel Dave: Most studies showing positive outcomes with diabetics and diet have not used low carb diets but have rather limited calories and fat content. A low carb diet could be positive for Type 2 diabetics in terms of body weight, but there are no long-term studies yet. A high fat diet for patients with Type 2 diabetes with an abnormal lipid profile and some degree of coronary artery disease would not be recommended. It could also be quite risky for Type 1 diabetics because of hypoglycaemia.

Can you explain what carbohydrate resistance is?

Tim Noakes: My opinion is different from the traditional teaching. Carbohydrate resistance is traditionally described as someone who is unable to take glucose out of the blood stream and store it in their muscle and liver.

I disagree with this explanation: I think we’re all born with varying degrees of carbohydrate resistance, and the children who get really fat very young are the ones who are most carbohydrate resistant. The carbs they take in are simply stored as fat. That’s the first group.

The second group is people who become pre-diabetic at 30 or 40, and then they become diabetic at 50. They are overweight, and that’s a marker of the high carbohydrate diet. They eat a high carb diet, they are carb resistant and it gets more and more severe until they become diabetic.

I think it’s genetic, and the reason I think that is because in my case, although I’ve lost weight, I’m still carbohydrate resistant – I can’t go back to eating carbs. 

Genevive Jardine: I have seen that lowering carbohydrate intake to 130-150g per day (of the right type of carbs) can have a very beneficial effect on blood glucose control, medication reduction and weight loss, but this needs to be managed individually. There may be people who respond well to a very low carb diet (50g a day), but the issue is how long can it be sustained?

Joel Dave: Patients with diabetes do not need to cut out all carbs, but rather limit portion sizes and learn to carb count.

What if you have high cholesterol? Isn’t it dangerous to eat so much fat?

Tim Noakes: Firstly, the theory that high cholesterol is a good predictor of heart disease is not true – it’s a relatively poor predictor. A far better predictor is your carbohydrate status. Everyone knows this – if you’re diabetic or pre-diabetic, your risk of heart disease is increased. Diabetes, hypertension and heart disease are linked, but most heart attacks occur in people with cholesterol below 5. It’s very frustrating, because the public has got the wrong idea.

A high fat diet corrects everything, in my opinion – your HDL goes shooting up, your triglycerides come shooting down and that HDL to triglyceride ratio improves dramatically: that’s one of the better predictors of heart attack risk.

The LDL small particles are the killers, and on a high fat diet, those go down. Your total cholesterol can go up, but that’s because your HDL has gone up, and the large, safe LDL particles have gone up. So unless you measure all those variables: HDL and LDL and triglycerides and glucose tolerance, you can’t judge the effects of the diet.

Joel Dave: In a large study of 52 countries, smoking and the ratio of LDL to HDL cholesterol were the two strongest predictors of heart attack risk. Carbohydrate status (diabetes) was also a risk factor, but not as strong as LDL:HDL ratio. The improvements in lipid status possibly observed in the early phases of this diet are more likely due to weight loss than the high fat content. There is no long-term scientific evidence for the safety and efficacy of a high fat diet to maintain a normal lipid profile.

What carbs do you eat?

Tim Noakes: The good carbs are veg – that’s it. Sweet potatoes (not regular potatoes), butternut, squash and then I also eat dairy: milk, cheese, yoghurt. I don’t eat any fruit except apples, but that’s because I severely restrict my carbs. You’re not cutting out nutrients if you eat nutrient-dense foods like liver, sardines, broccoli and eggs – those are the most nutrient-rich foods you can eat.

You can get vitamin C from meat if it’s not over-cooked. The key is that you eat lots of fat, and you don’t avoid the fat. I eat lots of fish, like salmon and sardines. And you want to eat lots of organ meats – that means liver, pancreas, kidneys, and brains if you can get them, but particularly the liver. Liver is very nutritious.

Is this diet possible for people who don’t have a lot of money?

Tim Noakes: You don’t have to eat meat every day – you can eat sardines and kidneys, for example, which are both very cheap.

Could the positive effect of a low carb diet on insulin resistance be because of the weight loss and not because of the new diet?

Tim Noakes: No, absolutely not. Because it happens within one meal – your insulin requirements go down within one meal, because you’ve shut off the production of glucose by not eating carbohydrates.

Joel Dave: In overweight patients with Type 2 diabetes, the best way to achieve a sustained long-term reduction in insulin requirements is with weight loss.

What is wrong with the old fashioned idea of a balanced diet? Why does it have to be so extreme?

Tim Noakes: If you’re diabetic, you have a problem with metabolising carbohydrates. You have to understand that if you want to live a long life and have minimal complications, you want to minimise your carb intake.

Start at 50g a day. What that looks like is two eggs for breakfast, with some fish – salmon or sardines, and some veg. And dairy: cheese or yoghurt. That will sustain you until early afternoon.

For lunch, I think you should have salad and some more protein and fat – and exactly the same for dinner. Chicken, cheese, nuts, salad, tomatoes, broccoli. It’s an incredibly simple way to eat, but you don’t get bored.

Once you’re on this diet, you feel so good, and you get rid of all these aches and pains and minor illnesses: you won’t want to go back. If you do go back to eating carbs, you’ll put on the weight again. It’s not a diet; it’s a lifelong eating plan. It’s not a quick fix.

I think the diabetics who live to 80, 90, 100 are the ones who eat this kind of diet.

Genevive Jardine: The biggest issue I have with a very low carb diet is that I haven’t met one person who naturally eats this way. This may explain why there is no data to test the long-term effects. This way of eating takes serious commitment and effort: once a person has chosen it, there’s no going back, as Prof. Noakes suggested. The biggest battle I have in my practice is fostering sustainable healthy eating habits - a lot of damage is done through on-off dieting. If someone chooses this way of eating, they need to understand the long-term commitments.

Joel Dave: Most studies showing positive outcomes with diets in patients with pre-diabetes or diabetes have individualised diets tailored to them, not low carb diets.

(This article was originally published in Sweet Life magazine, Sweetlifemag.co.za)

For any further information, please contact the Pick n Pay Health Hotline registered dietitian, Leanne Tee on 0800 11 22 88 or e-mail her on healthhotline@pnp.co.za.

To find a registered dietitian in your area, go to the ADSA (Association for Dietetics in South Africa) website at www.adsa.org.za

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