Low Carb Diets – Do they work?

Written By: Gloria Tsang, RD

Title: Founding Registered Dietitian

Alumni: University of British Columbia

Last Updated on:

Fad diets come and go – the Low Carb diets have received a lot of attention in the past few years yet again – since it became unpopular in the 70s. With millions of book sales and aggressive marketing campaigns, many people turn to these Low Carb diets such as the Atkins diet and the Zone. Do we know if they are safe and effective?

Low Carb Diets – the theory behind

The key message these Low Carb Diets conveys is that carbohydrates promote insulin production, which in turn results in weight gain. Therefore by reducing carbohydrate intake, we will lose weight.

The truth is: by eating a Low Carb diet, you do not provide sufficient carbohydrates to your body for daily function. Therefore it will start burning the stored carbohydrates (glycogen) for energy. When your body starts burning glycogen, water is released. Therefore the drastic initial drop of weight at the beginning is only water you lose as a result of burning glycogen.

Some Low Carb diets are indeed high in fat!!! Some of these diets promise that you may eat as much meat, butter and cream as you want. There is no way for someone to eat that much fatty food and justify that it is healthy to do so!!!! Numerous well-proven scientific research showed that diets high in fat and saturated fat can increase the risk of heart disease.

In addition, some Low Carb diets such as the Atkins Diet lump all carbohydrate foods together and give it a bad name. For example, the Atkins diet limits carbohydrate intake to just 20g daily at the beginning (vs 130g recommended level by the National Academy of Sciences’ Institute of Medicine). Most grains, fruits, beans, potatoes, rice, pastas, some vegetables are all excluded from this diet. Fruits and Vegetables especially, are rich in fiber as well as antioxidants such as Vitamin C, carotenoids, flavonoids, etc which are essential in the prevention of heart disease and cancer.

Why do people lose weight initially on a low-carb diet?

The truth is – in addition to losing water drastically at the beginning, these low-carb diets are often calorie-restricted!!! Followers only eat an average of 1000 – 1400 calories daily; compared to an average intake of 1800 – 2200 calories. To lose 1 lb a week, you only need to eat 500 fewer calories per day than you metabolize. Therefore, it doesn’t matter if you eat a high or low carb diet, you will lose weight if you restrict your calories to less than you need. One easy way to lose 500 calories a day without restricting food? Physical exercise. Speak to your registered dietitian – they are able to calculate how much calories you minimally need per day. Read 10 Tips for Easy Weight Loss.

Low Carb Diets Key Message

Short term drastic weight loss is often not lasting. If you are following a low carb diet, try not to over-restrict the “healthy carb” such as beans, whole grains, whole fruits and vegetables.

Bottom Line – Low Carb Diets and Weight Loss

The traditional weight loss method emphasizing a well-balanced diet with a variety of foods including grains, fruits & vegetables, dairy and meat/fish, low in total fats, saturated fats and trans fats in addition to being physically active can result in long lasting weight loss and improved health. This doesn’t sound too exciting but it works!

Low Carb Diets – any uses?

Yes! Studies and clinical practice showed that lower carb diet is important in diabetes management. In addition, a study published in the American Journal of Clinical Nutrition Aug 2004 found that despite the ineffectiveness of a low glycemic index diet on weight loss, it can reduce LDL cholesterol (the Bad cholesterol) by 10%.


cholesterol, glycemic index, lose that weight, low carb


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