The idea of being able to eat as much meat and cheese as you want and lose weight is pretty appealing to most people; hence the popularity of low-carb diets. But does “beefing up” your plate really result in weight-loss, and are there any negative spin-offs when cutting down on carbs?

We put these questions and more to our CalorieKing dietitian, Joan Bushman. Check out her helpful responses to commonly asked questions about low-carb diets below.

Q1. Does cutting carbs really result in weight-loss? Does the weight stay off?

Cutting carbs will often result in rapid short-term weight loss – but there are problems with this. Low-carb/high-protein diets force your body into a state called ketosis – this is when your body uses fat instead of carbs as an energy source. During the early stages of ketosis, small body fat losses are exaggerated by large water losses – rapid weight loss is a result.

If you compare a regular diet and a low-carb diet based on the same number of calories, the fat losses are exactly the same. But as much as 7 lbs or more can be lost in the initial stages of a low-carb diet because of water loss. Because it’s water rather than body fat, however, it’s not “real” weight loss and is easily regained when the diet is relaxed.

Although it involves some patience, losing weight gradually is better. Quick weight loss may be a temporary motivator but when the weight plateaus or comes back, the metabolism is negatively affected. Go slowly and eat healthy foods from all the major food groups. Include wholegrain breads and cereals, fruit, vegetables, and low fat milk or a moderate amount of soy in your diet. Keep the big picture in mind, not just the “quick fix”.

Q2. Are there any negative side-effects to a low-carb diet?

That depends on what you consider “low-carb”. Reducing your carb intake to 40% of total calories may be okay, especially if you plan to cut back on sugar and white flour and include lots of high-fibre vegetables and fruit. But if you’re thinking of reducing your carb intake to 100g or less per day and proportionately increasing your protein and fat intake (especially saturated fat), then negative health effects may result. These may include constipation, high blood cholesterol levels, gout, dehydration, kidney problems, ketosis, immune deficiency diseases, colon cancer and other cancers – not a nice pay-off really! The high acid level in a high protein diet can also leech calcium from bone, and increase the risk of osteoporosis.

Tiredness and a lack of energy can also result from insufficient carbohydrate intake. For most types of exercise the body’s muscles use mainly glycogen – the storage form of carbohydrate. When glycogen stores get depleted, so can your energy.

Q3. Is there a danger of missing out on nutrients from carbohydrates on a low-carb diet?

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Yes, missing out on important nutrients is often a result of extreme dieting, including the sort of low-carb dieting in which dieters consume as little as twenty grams of carbs in the initial phase.

Carbohydrates are the basis of grains, fruits and vegetables, and milk, which has a significant amount of carbohydrate in the form of lactose. When you eliminate or severely limit these foods, you are likely to have a grossly inadequate intake of many essential vitamins, minerals, antioxidants, fibre and water that carbohydrates provide. You’re also limiting the variety of foods that make eating more enjoyable.

Also remember that nutritional supplements can never replace the hundreds of plant phytochemicals (which include anti-cancer agents) in naturally-occurring carbohydrate-based foods.

Q4. Why is cutting carbs suddenly the best way to lose weight? What happened to cutting fat?

Partly it’s to do with new research that shows we consume too many refined carbohydrates, but generally it’s because people like to think carb-cutting is the “latest and greatest” remedy for weight gain. However, like all latest-and-greatest remedies, this one is flawed. When low-fat diets were popular, people ate too many high-sugar foods to make up for calorie and satisfaction deficit. On low-carb diets, people now eat too many high-fat foods.

Although current marketing would lead us to believe that fat is now the “good guy” and carbs are the “bad guy”, watching fat intake is still important. It’s the type of fat that’s the key – avoid deep-fried foods and saturated fats and instead include healthy fats, such as olive oil, canola oil and omega-3-fats (in flax oil and some fishes).

However, there is something to be said for cutting out “bad” carbs as well – it’s good to cut down on sources of refined carbs, such as cakes, pastries, lollies, soft drinks and table sugar. We Australians eat too many of those! But we should also increase our intake of healthy carbs from natural food sources.

Q5. Low-carb diets seem to be full of bacon, red meat and eggs. Aren’t those foods high in fat and cholesterol?

When low-carbers severely restrict or cut out healthy carbohydrate foods, such as wholegrain breads and cereals, potatoes, fruit, vegetables and milk, there’s not much left to eat other than meat, poultry, eggs and cheese – and larger servings are usually consumed.

These foods are generally high in fat (including artery-clogging saturated fat) as well as cholesterol and sodium. When eaten in excessive amounts, the risk for heart disease and a host of other ailments is generally increased. These potential ill-effects are likely to be made worse by any lack of fruit, vegetables and wholegrains, which provide protective nutrients and antioxidants.

Q6. If you really love your carbs, do you have to give them up to lose weight effectively?

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It’s common for people to think they have to give up the foods they enjoy to lose weight. But this isn’t true. In fact, it’s wise to eat some of the foods you love, but there are tricks in doing so. For instance, if you love pasta, cut back on portion size and make up for the difference by topping it with veggies and low-fat protein. If you love bread, go for the high fibre or whole-grain varieties and, of course, use low-fat toppings.

Watching overall calories and having a balance of healthy carbs, lean protein and healthy fats is a great dietary approach for most people. Deprivation of any food group – especially one you love – is just asking for failure.

Q7. Is there a healthy way to go low-carb?

If you cut carbs by restricting refined flours and sugary foods and drinks, but still include plenty of healthy carbohydrates such as wholegrains, fruits and vegetables, then going low-carb could be a healthy option. However, you still need to include at least 100g of carbs a day in your diet. Over time that amount should be gradually increased. If the diet restricts carbs to less than 100g per day, it’s not a healthy option.

To reframe the question… Is there a healthy way to diet? Yes. Increasing your physical activity, and watching calories and portion sizes, while including healthy and nutritious foods from all of the food groups is a healthy way to lose and maintain weight. You should do all of those things if you want your low-carb diet or any other diet to be successful in the long term.

Calorie King
CalorieKing's mission is to provide the best information, tools and education to Australians to help them conquer their weight.

CalorieKing is the brainchild of Allan Borushek, registered dietitian, co-found here at food.com.au and author of "Allan Borushek's Pocket Calorie & Fat Counter", Australia's best-selling calorie counter for over 30 years.

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