What can I do to increase my chances of losing unwanted weight and keeping it off?

This answer is brought to you by many of the Australian nutrition professionals who regularly contribute to a nutrition email discussion group.
Date of last revision: June 2004.

Despite decades of research, we still don't fully understand why some people gain weight more easily than others, and also have greater trouble losing excess weight.

It is known that body fat levels are increasing in Australia, along with the rest of the developed world (and increasingly in the developing world too). For example, in 1990 fewer than 10% of Australian adults were obese, while in 2001 the corresponding figure was more than 16%. In 2003 the Worldwatch Institute reported that, possibly for the first time in human history, the number of overweight individuals worldwide rivals the number of underweight. Clearly, something is wrong with our diet and/or lifestyle.

However, it is known that avoiding excessive energy (i.e. kilojoule) intake is critical to weight control. That is, you will inevitably gain weight if your energy intake exceeds your energy output.

But this doesn’t mean “crash dieting”—attempting to lose huge quantities of weight in a short time. Gradual weight loss, at a rate of 0.5–1.0 kg per month, is most likely to lead to sustainable weight loss, because the body hardly ‘notices’ such a low rate of change. By way of contrast, rapid weight reduction stimulates hunger (the body interprets sudden weight loss as impending starvation and does all it can to encourage higher food intake). A slow rate of weight loss also means that you can eat enough food to ensure adequate intake of essential nutrients such as vitamins, minerals and dietary fibre.

Also, while reducing your food intake will help in weight control, it may not be sufficient in itself—you must still ensure that your level of physical activity takes your energy expenditure above your energy intake. It is difficult to over-emphasise the importance of physical activity, not only in weight control but for general health and fitness as well.

The simplest and most appropriate physical activity for most people is walking—just adding 30 minutes of brisk walking to your daily activity pattern may be enough to tip the ‘energy balance’ in favour of reducing weight.
[For more on this, see the FAQ on activity and weight control ]

If you lose 0.5–1.0 kg of excess body fat per month, your weight will have come down by about 9 kg in a year. For someone whose initial weight was 90 kg, this represents a 10% weight reduction, enough to make a substantial difference to your health and ‘metabolic’ fitness (i.e. blood pressure, cholesterol, triglycerides and so on).

Once your weight has stabilised at the new (lower) level, it is essential that you continue with your new lifestyle of slightly lower food intake and increased physical activity, or the weight will simply go back on. In other words, there is no point going on ‘a diet’; rather, the changes you made to lose weight must now be a permanent part of your life.

This will not be easy—the propensity (urge) to eat has been described by one obesity expert as “somewhere between the propensity to breathe and the propensity to have sex. It's much worse than stopping smoking." This means that people who have lost substantial quantities of body fat must learn (or relearn) to eat according to ‘hunger’ (the body’s way of letting you know that you have a physiological need for food), rather than according to the desire to eat.

Although the solution seems straightforward (eat less and increase physical activity), as already mentioned in this FAQ, losing weight is difficult enough in the first place; keeping it off is even harder.

If we fully understood the actual cause (or causes) of the worldwide increase in body fat levels, we would be in a better position to develop strategies to halt the epidemic (and perhaps even begin reversing it). Clearly, both diet and lifestyle (particularly physical activity—or rather a lack of activity) are involved in the obesity epidemic, but the exact role of diet is still very controversial.

Three major schools of thought exist on the importance of diet in preventing and treating obesity:

1. For many years the emphasis has been on reducing fat intake and increasing the consumption of carbohydrate foods, particularly breads and other cereal foods such as rice and pasta (preferably whole grain), but also potatoes and high-carbohydrate vegetables (including legumes) and fruits. Consumption of low-energy vegetables (e.g. carrots, broccoli, tomatoes) has also been encouraged. High carbohydrate intake may be protective in at least two ways: First, carbohydrate provides less than half the energy (kilojoules) per gram that fat provides. Second, foods such as breads, cereals, fruits and vegetables are rich in dietary fibre. High fibre intake should assist by causing a feeling of 'fullness' in the stomach for relatively little kilojoule intake, so energy intake may be self-limiting.
2. Instead of emphasising ‘low fat’, some nutritionists now favour 'medium fat', but low saturated fat intakes, with much of the saturated fat (found in foods such as sausages and other fatty meats, high-fat dairy products, biscuits and cakes) being replaced with ‘heart healthy’ fats such as monounsaturated fats (found in large quantities in canola and olive oil, avocadoes and most nuts) and omega-3 fats (found in significant quantities in dark-fleshed fish, but also present in canola, walnuts and linseed).
3. A third approach to weight control involves substantially reducing carbohydrate intake. These ‘low-carbohydrate’ diets (such as the Atkins, South Beach, Zone diets) seem to have captured the imagination of the general public, but they remain very controversial among orthodox nutritionists.
   [For more on these and similar diets see the FAQ on popular diets.]

Satisfactorily resolving this debate will require many years of scientific research. So in the face of the current uncertainty, what should people do if they want to lose some excess body fat (or avoid putting it on in the first place)?

Perhaps the best advice that can be given now to people who want to avoid gaining weight, or safely lose weight and keep it off is to follow the advice given above (gradually lose weight by slightly reducing food intake and increasing physical activity) and also adhere to the dietary guidelines for Australians:

Enjoy a wide variety of nutritious foods:

• Eat plenty of vegetables, legumes and fruits
• Eat plenty of cereals (including breads, rice, pasta and noodles), preferably wholegrain
• Include lean meat, fish, poultry and/or alternatives
• Include milks, yoghurts, cheeses and/or alternatives
• Reduced-fat varieties should be chosen, where possible
• Drink plenty of water
• Limit saturated fat and moderate total fat intake
• Choose foods low in salt
• Limit your alcohol intake if you choose to drink
• Consume only moderate amounts of sugars and foods containing added sugars

Prevent weight gain: Be physically active and eat according to your energy needs:

Finally, many people seem to find it easier to lose weight if they have the support of like-minded people. Joining a reputable group such as Weight Watchers may improve your chances of losing weight in the first place, and then keeping it off.

For more information Nutrition Australia recommends:

• Weight for a Change
• Eating Activity, Sport and You
• Dietary Guidelines for Australians: http://www.nhmrc.gov.au/publications/synopses/n4syn.htm

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Disclaimer: This material is provided on the basis that it constitutes advice of a general nature only. It is not intended to replace the advice of a physician or a dietitian.