The idea of being able to eat as much meat and cheese as you want and lose weight at the same time is pretty appealing; hence the popularity of low-carb diets. But does “beefing up” your plate really result in weight loss, and are there any negative consequences of cutting down on carbs?
We put these questions and more to our dietitian, Joan Bushman. Check out her helpful responses to commonly asked questions about low-carb diets.
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-fat diets force your body into a state called ketosis – this is when your body uses fat instead of carbs as its energy source. During the early stages of ketosis, small body fat losses are exaggerated by large water losses – resulting in rapid weight loss.
If you compare a regular diet and a low-carb diet based on eating the same number of calories per day, the fat losses you’d see as a result would be exactly the same. But as much as 7 lbs or more can be lost in the initial stages of a low-carb diet due to water loss. When you eat fewer carbs, your body holds onto less water. However since it’s water rather than body fat you’re losing, it’s not “real” weight loss and is quickly 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, your metabolism is negatively affected. Go slowly and eat healthy foods from all the major food groups. Include whole grain 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?
This depends on what you consider “low-carb”. Reducing your carb intake to 40% of your total calories might be okay, especially if you plan to cut back on sugar and white flour and still 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 your bones, and increase your risk of osteoporosis.
Tiredness and a lack of energy can also be a consequence of insufficient carbohydrate intake. For most types of exercise, your body’s muscles use mainly glycogen as fuel – the storage form of carbohydrates. When your glycogen stores are depleted, so is your energy.
Q3. Is there a risk of missing out on nutrients from carbohydrates on a low-carb diet?
Yes, missing out on important nutrients is often a result of extreme dieting, including the sort of low-carb dieting requiring you to consume as little as 20 grams of carbs per day in the initial phase.
Carbohydrates are the basis of grains, fruits and vegetables, and milk, which contains a significant amount of carbohydrates in the form of lactose. When you eliminate or severely limit these foods, you’re likely to have a grossly inadequate intake of many of the essential vitamins, minerals, antioxidants, fibre and water which carbohydrates provide. You’re also limiting variety in your diet, which makes eating more enjoyable.
Also remember 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 due to new research which 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 deficits. Following low-carb diets, people now eat too many high-fat foods.
Although current marketing leads you to believe fat is now the “good guy” and carbs are the “bad guy”, monitoring your 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 oily fish).
However, there’s something to be said for cutting out “bad” carbs – it’s good to cut down on refined carbs, such as cakes, pastries, lollies, soft drinks and table sugar. Australians eat too many of these! But you should also increase your intake of healthy carbs from natural food sources at the same time.
Q5. Low-carb diets seem to be full of bacon, red meat and eggs. Aren’t these foods high in fat and cholesterol?
When low-carb dieters severely restrict or eliminate healthy carbohydrate foods, such as whole grain 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, your risk of heart disease and a host of other ailments is generally increased. These potential ill-effects are likely to be made worse by the lack of fruit, vegetables and whole grains being consumed, which provide protective nutrients and antioxidants.
Q6. If you really love your carbs, do you have to give them up to lose weight effectively?
It’s common for people to think they have to give up foods they enjoy to lose weight. But this isn’t true! In fact, it’s wise to eat all of the foods you love, but in moderation. 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 use low-fat toppings.
Watching your overall calorie intake and eating a balance of unrefined carbs, lean proteins and healthy fats is a great dietary approach for most people. Deprivation of any food group – especially one you love – is just a recipe 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 whole grains, fruits and vegetables, then going low-carb can be a healthy option. However, you still need to include at least 100g of carbs per day in your diet. Over time, that amount should be gradually increased. If your 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 your calories and portion sizes, while including healthy and nutritious foods from all food groups is a healthy way to lose and maintain weight. You should do all these things if you want your low-carb diet (or any other diet) to be successful in the long term.