Low-Carbohydrate Diets
Over the last few years there has been an increase in the publicity of low-carbohydrate diets to achieve weight loss. However, the basis for these diets may be misleading and scientific evidence of their long-term effectiveness and safety has not been established. For many reasons these diets may not be considered appropriate substitutes for a recommended lifelong pattern of healthy eating.
There are a number of different low-carbohydrate diets around (sometimes called "ketogenic" diets), including "Dr Atkins' New Diet Revolution", "Protein Power", "The Carbohydrate Addict's Diet". These diets promote low intakes of carbohydrates with varying moderate/high amounts of fat and protein, to achieve weight loss.
Low-carbohydrate diets do lead to some weight loss within the first week or so, which can be very encouraging, but this is due to a greater loss of body water than body fat. When these diets end, water weight is regained.
Low-carbohydrate diets tend to also be low in energy (measured in kilocalories or kilojoules). As with all "low energy" diets, low-carbohydrate diets can result in loss of body fat if they are continued long enough. However, this longer-term weight loss has been shown to be the same as for other low energy diets. So, the actual proportions of protein, carbohydrate or fat do not seem to play a major role and other factors like the duration of the diet and the amount of exercise may be more important in determining the amount of weight lost.
Just because a diet achieves weight loss, does not mean it is necessarily a healthy diet.
Low-carbohydrate diets identify carbohydrates as being the "bad guys" in promoting overweight. Certainly, decreasing the consumption of carbohydrate foods that are also high in fat (eg cakes, pizzas, hot chips) is to be encouraged.
However, the reasoning for excluding carbohydrates that are known to be healthy such as grain foods (wholegrain bread, brown rice), fruit and vegetables is not reliable.
These healthier carbohydrate foods are the major sources of glucose, fibre and many minerals and vitamins. They also contain hundreds of 'phytochemicals', whose value to health is not yet fully understood, but which may also be of great importance.
| Carbohydrate |
|
Increased consumption of a wide range of plant-based foods (high in carbohydrates) is associated with improved health and greater life expectancy.
Low intake of these carbohydrates, as in low-carbohydrate diets, can result in inadequate intake of vitamins, minerals and fibre.
Some of low-carbohydrate diets recommend high intakes of protein-rich foods (eg ham, chicken, cheese, eggs). However, high levels of animal protein are often associated with high levels of saturated fat, increasing the risk of heart disease and some cancers. Also long-term consumption of excessive protein intake may damage the kidneys.
Conditions caused in the body by eating only small quantities of carbohydrates can also lead to tiredness, constipation and impaired liver and kidney function. Recent research has also shown that low-carbohydrate diets significantly reduce athletes' ability to perform.
All in all, the most effective strategy to lose weight is to create a healthy lifestyle pattern that combines reduced energy intake with increased physical activity.
New Zealand Food and Nutrition Guidelines for Healthy Adults:
- Maintain a healthy body weight by eating well and by daily physical activity *
- Eat well by including a variety of nutritious foods from each of the four major food groups every day:
- Eat plenty of breads and cereals (preferably wholegrain)
- Eat plenty of fruit and vegetables
- Have milk and milk products in your diet (preferably reduced or low-fat options)
- Include lean meat, poultry, seafood, eggs or alternatives. - Prepare foods or choose pre-prepared foods, drinks and snacks:
- With minimal added fat, especially saturated fat
- That are low in salt; if using salt, choose iodised salt
- With little added sugar (limit your intake of high-sugar foods). - Drink plenty of liquids each day, especially water.
- If choosing to drink alcohol, limit your intake.
- Purchase, prepare, cook and store food to ensure food safety.
* At least 30 minutes of moderate intensity physical activity on most, if not all, days of the week and, if possible, add some vigorous exercise for extra health and fitness.
Within these guidelines many different eating patterns can be chosen to suit your preferences. Watch the serving sizes and enjoy a variety of food.
Judith Morley-John
Food 2 Go - February 2004
