All about low carb

What’s the story?

Low-carb diets certainly aren’t new. Most people have heard of Atkins, and those who are a little older, perhaps the Scarsdale Diet. Back in the 1960s there was the Russian Air Force Diet, the Drinking Man’s Diet and even Leben Ohne Brot (Life Without Bread), all low in kilojoules and carbs.

Although these approaches were superseded for a time by low-fat diets, we are now seeing a resurgence of low-carb diets, with LCHF and keto diets being the popular modern-day versions. But are these diets really the solution to our weight and health issues? And are there any downsides, particularly for people with diabetes?

What is a low-carb diet?

There’s no formal definition of ‘low carb’, and the term can be used for diets as low as 20g of carbs a day, or for those with a more modest reduction in carbs (less than 45 per cent of total energy intake – the government recommendation).

LCHF and keto diets belong to the former category and generally exclude all grains, legumes, starchy vegetables, most fruits and carb-containing dairy foods such as milk, replacing them with non-starchy vegies, meat, poultry, seafood, eggs, olive oil, coconut oil, nuts and dairy foods such as cheese, butter, cream and Greek yoghurt. They encourage choosing fatty cuts of meat (preferably organic and grass-fed) and full-fat dairy foods.

What’s good about going low carb?

Low-carb diets cut out the processed carbohydrates and added sugars none of us need.

Despite any controversy and differences of opinion, pretty much everyone agrees there are many carbs that shouldn’t feature regularly in a healthy diet. These include refined carbs (think biscuits, cakes, pastries, highly processed breakfast cereals and white bread) and added sugars (such as confectionery and sugar-sweetened drinks). It’s likely most of the benefits of going low carb come from eliminating these from your diet, rather than going low carb per se.

What are the downsides of going low carb?

Low-carb diets restrict most of the foods we know are beneficial for good health, including whole grains, legumes, fruits and some vegetables. Research has shown eating more of these foods is associated with a reduced risk of many chronic diseases, including cardiovascular disease, type 2 diabetes and some types of cancer.

There’s also evidence low-carb diets high in animal foods can worsen insulin sensitivity, increase type 2 diabetes risk and increase overall mortality risk and the risk of dying from heart disease and cancer.

Restricting whole grains and legumes and eating a lot of animal foods can also have negative effects on your gut bacteria, which in turn may increase the risk of future health problems, including bowel cancer.

Finally, very-low-carb diets can have some pretty unpleasant side effects, including constipation, bad breath, headaches and dehydration as a result of ketosis (breaking down fat for energy).

They can also lead to poor energy levels and fatigue, which in turn make it difficult to exercise.

Will a low-carb diet help me to lose weight?

Most likely, yes. In fact any eating plan that cuts out major food groups is likely to lead to weight loss, and this is particularly the case for carbs, which are found in so many of the foods we commonly eat.

Cut out breads, cereals, grains, fruit, starchy vegetables, legumes and some dairy products and there isn’t much left to eat. So weight loss is bound to occur.

However, studies show that while low-carb diets often lead to more rapid initial weight loss, in the longer term (more than 6-12 months) they don’t appear to be any better than low fat, or other types of energy restricted diets. They can also be pretty hard for most people to stick to. And unless you can continue your new way of eating for the long term, it’s unlikely your weight-loss efforts will be sustained.

Will a low-carb diet help me manage my diabetes?

Any diet that helps you lose weight is very likely to lower blood glucose levels, by helping your insulin to work better.

Low-carb diets are no exception, and there is certainly some evidence to show low-carb diets (including the very-lowcarb diets) can help with improving blood glucose levels and blood fats, and reducing the medication of needs in people with type 2 diabetes.

But other diets, including Mediterranean and low-fat vegetarian diets, have also shown similar benefits. We also don’t know the long-term effect of a very-low-carb diet.

Those in favour of low-carb diets for diabetes say cutting carbs is the answer because these are the foods that directly affect our blood glucose levels. When we eat carbohydrate, it is broken down during digestion to glucose, which then appears in the bloodstream. So it might seem logical that cutting out carbs will help to lower blood glucose levels. And to some extent, this is the case.

But if you have type 2 diabetes, the reason you don’t deal with carbs in the same way as someone without diabetes does is because of underlying insulin resistance. So the aim of making any dietary or lifestyle changes should be to improve how insulin works in your body.

Losing weight and exercising both improve insulin resistance, but so do the types of food we eat. And there is evidence low-fat, high-fibre and plantbased diets improve insulin resistance, while high intakes of saturated fat and red meat can worsen insulin resistance.

What’s more, people who are choosing to follow a vegan diet (which is typically higher in carbohydrate and lower in fat) seem to have the lowest risk of developing type 2 diabetes. So while a very-low-carb diet may work in the short-term, it may not be the best solution there is to managing diabetes in the longer-term.

Still want to go low carb?

If you still think following a low-carb diet is the right approach for you to take, there are some ways to optimise the benefits and reduce the downsides.

This mainly comes down to considering where you get your protein and fat.

A low-carb diet high in animal fat and protein has been found to increase your chances of dying of any cause by 23 per cent, your chance of dying of heart disease by 14 per cent and your chance of dying of cancer by 28 per cent. A vegetable-based low-carb diet, on the other hand, is associated with a reduced risk of death from all causes and from heart disease.

So if you are going to embrace low carb, you need to make sure most of your fat and protein comes from plants!

You can do this by:

• Avoiding processed meats and replacing red meat with plant proteins such as tofu, tempeh, nuts and seeds.

• Getting most of your fat from avocado, nuts, seeds, olive oil and oily fish, rather than fatty meats, palm and coconut oil.

• If you’re cutting out fibre-rich foods such as grains, legumes and fruit, ensure you’re getting plenty of vegies in your meals.

• Including small amounts of quality carbs, rather than cutting carbs altogether – good choices include legumes, fruit, starchy vegetables and minimally processed whole grains such as quinoa, barley and rolled oats.

If you’re taking insulin or medication to manage your diabetes, it’s essential to speak to your doctor before you consider going low-carb, as your medication will need adjusting to avoid the risk of hypos. It’s also important to monitor your blood glucose levels regularly when making any significant changes to your eating plan.

Your doctor will need this information in order to make adjustments to your medication.

In summary

Low-carb diets are one way to lose weight and improve blood glucose levels, but they are not the only way and may come with longer-term health risks. In fact, there’s good evidence for the health benefits of many carbohydrate foods, including legumes, whole grains, and fruit and vegetables, and research points towards a plant-based diet being the best type of eating plan for long-term health and chronic disease prevention.