By Judy Davie
**”My husband wants to lose about 10kg over the next six months. He says he’s going to exercise every day and cut out carbohydrates completely. Is this safe?”
— Sophie**
If your husband was able to stick to a carb-free diet and exercise every day for six months, he would lose weight but it’s unlikely he’ll be able to stick to it or be able to exercise strenuously while on it. And if he did stick to it and lose the weight, there’s every chance he’ll regain the weight soon after.
Carbs feed the brain
Our brains rely on carbohydrate for food, which is probably why we like it so much. Of all our organs the brain is the most energy-demanding and unlike muscle, it can’t survive on fat for fuel. It relies on glucose, converted from carbohydrates. Once there is no more carbohydrate to draw upon, the brain will head off to the liver for glucose reserves, but once that’s run out it has to find fuel elsewhere. When the brain is completely denied carbohydrate on a high protein/fat diet, it has no choice other than to use ketones, chemicals produced when fat is broken down by the body. It may seem like good news converting fat to brain fuel, but high levels of ketones are a serious risk for pregnant women and the brain function of their unborn child. They are also considered dangerous to the health of children and over the long term can impair mental function in adults. Anyone deprived of carbohydrates over a period of time is likely to feel headachey, light-headed and possibly a little depressed.
Why depressed?
Carbohydrates help produce the “feel good” brain chemical serotonin, which is also a precursor to sleep. Quality complex carbohydrates in the form of wholegrain cereals are also a good source of B vitamins and magnesium, nutrients that play a vital role in the function of the nervous system. A deficiency in either or both may lead to anxiety, stress and depression.
Physical performance
Muscles are also fuelled by glucose and while they are able to feast on fat, lean body tissue and water, glucose is by far their preferred source. If you want to increase your level of physical activity and maintain a regular fitness regime over the long term, you must include some “good quality carbohydrates” in your diet. Otherwise you’re likely to feel fatigued and lacking in physical strength.
Bowel health
Fruit and vegetables, wholegrains, pulses and legumes are all carbohydrate-rich foods. They are also the best sources of fibre available in the diet. Without fibre, the transit time of food passing through the stomach to the small and then large intestine is slowed. Complications include a build-up of toxins, leading to, at best, constipation; at worst, bowel cancer.
Keeping it off
Low-carbohydrate diets are notoriously hard to maintain. Why? Because we like carbohydrates and our bodies need them. But even if your friend was to stick to the diet and shed the weight, what then? At some point he would have to reintroduce carbohydrates to the diet and, as we’ve seen with many Hollywood celebrities, it’s like opening the floodgates. Once they get a taste of it again, they’re off. Permanent weight loss can only ever be achieved when you change the diet to a style of eating that can be maintained all the time — and that will not happen when a whole food group is eliminated.
What type of carbohydrates are best?
Fruit, vegetables, legumes, pulses and wholegrains are all first-class carbohydrates, for all the reasons mentioned and many more, including being nutrient-rich, low in energy, high in fibre and packed with antioxidants. Include foods such as wholegrain bread, brown pasta, quinoa, cracked wheat, sweet potato, sweet corn, barley, rolled oats, lentils, beans, loads of multi-coloured vegies and a couple of pieces of fruit each day and eliminate all the highly processed carbohydrates and sugar-rich foods, including white bread, white pasta, large baking potatoes, cakes, crackers and biscuits, soft drinks, alcohol and beer.
When should carbs be eaten?
As they are the body’s preferred source of energy for brain health and physical performance, eat more carbohydrates for breakfast and lunch and less at night. Some people believe carbohydrates should be eliminated after 5pm, but as they can aid a good night’s sleep, there is definitely some merit in eating a small amount with the evening meal.
How much carbohydrate?
If you include no less than 40 percent carbohydrates in your diet, you should easily and healthily be able to lose weight, exercise, think clearly and feel good all at the same time.
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