Weight loss - some common misconceptions

Health risks

More Australians are overweight or obese than ever before, and the numbers are steadily increasing. Around 64 per cent of men and 47 per cent of women are carrying too much body fat. This means that the incidence of obesity-related disorders, such as coronary heart disease and diabetes, is also on the rise. The popularity of crash dieting has promoted many misconceptions about weight loss. Most of these misconceptions contribute to unhealthy weight loss behaviours.

A recent analysis of deaths in the United States (from their National Health and Nutrition Examination Survey) suggests that being overweight may not increase your risk of dying. This finding is contrary to past research. They estimated the numbers of premature deaths linked to weight in the year 2000. The findings were that underweight and seriously obese people have an increased chance of dying compared to normal weight people. Interestingly, however, being overweight, was associated with a slightly lower chance of dying for your age. The impact of obesity on mortality may have decreased over time, perhaps because of improvements in public health and medical care. The authors highlight that body weight may not be such an important risk factor for premature death and that fitness, smoking and saturated fat in your diet may be more significant.

Flegal KM et al. Excess deaths associated with underweight, overweight and obesity. Journal of the American Medical Association 2005;293:1861-1867
Mark DH. Deaths attributable to obesity. Journal of the American Medical Association 2005;293:1018-1919

How you became overweight
London University’s Professor Tom Sanders and author of a book “You Don’t have to Diet” has highlighted that the greatest of all myths is that “thin people are necessarily healthier than fat people.” Countries with higher prevalence of obesity do not necessarily have more coronary heart disease (CHD) e.g. Italians have less CHD than the slimmer Finns. And fat people are more likely to survive heart attacks than thin ones. It is not that being overweight in itself confers protection, though. Rather, it is how a person got that way. If you are fat because you have been eating a Mediterranean diet – all that pasta, wine and vegetables stewed in olive oil – then you are much better off than someone who is thin because they eat an energy restricted nutrient poor diet and smoke a lot.

Some dietary fats cause weight gain
Fats contain approximately double the amount of kilojoules (calories) per gram than carbohydrates or protein, making them a much more concentrated form of energy. It makes sense that, if you eat a lot of fat, you are more likely to put on weight than if you eat a lot of carbohydrate. The type of fat you eat may also be important. There is new evidence that animal fats (saturated fats) may be more 'fattening' than plant and fish fats. These fats appear to be more readily used by the body than saturated fat and are less likely to be stored as fat in the belly. They can also provide some health benefits.

Excess carbohydrates or protein can also be converted into body fat
If you eat more kilojoules than you use, you will put on excess weight whether those kilojoules came from fats, carbohydrates or proteins. Smoking also increases visceral fat (fat around internal organs in the abdomen). A study was published in the J Am Diet Assoc 2002 on 700 normal women followed up for 12 years. Women who ate a high-fat , high-sugar diet were 40% more likely to gain excess weight than those whose diets were high in fruits, vegetables and low fat milk. But women who drastically reduced fat did not seem to fare any better because some of the low fat foods were still energy dense due to increased sugar/carbohydrate content. Chronic dieters or "light eaters" tended to have fluctuating weights but had slightly increased rate of overweight.

Low, moderate or high carbohydrate diets?
In the short term, very low carbohydrate diets (such as Atkin's diet) (25% energy) can result in greater weight loss than the high carbohydrate diets, but in the long term weight loss differences appear to be minimal. Very Low carbohydrate diets can be unhealthy if too much animal fat is consumed and if plant foods are overly restricted . The long term safety of these diets is unknown. A study conducted by the CSIRO (Adelaide) in 2002 on 100 women has shown that moderate levels of carbohydrate (46% energy) and protein (34% energy) combined with low fat intakes (20% energy) is more effective at reducing weight in women, especially around the middle, compared with a high carbohydrate (63% energy) low fat diet (20% fat).

Rigid versus Flexible diets
Rigid diets are usually associated with stringent calorie counting and strict rules for food avoidance. Flexible diets emphasise portion size, eating slowly and less stringent restraint of intake. Which approach is better for weight loss? Rigid diets have been associated with greater problems of weight control and eating, including bingeing making dieters more prone to disinhibited eating. Flexible diets are less likely to be associated with disinhibited eating and tend to accept that transgressions can occur and deal with appropriately by compensating later in some way. The chance of success in long-term weight management is enhanced with the flexible approach.

Five food myths exposed

1. Potatoes make you fat - false
It was once advocated that the key to weight loss was the elimination of all high carbohydrate foods, including pasta, rice and potatoes. We now know that carbohydrates are the body's preferred energy source. Carbohydrates are broken down by the digestive system into a simpler substance called glucose, which is the body's main energy fuel. Excess glucose is stored in the liver and muscle tissue as glycogen to boost waning blood sugar levels between meals. Any glucose left over will eventually be converted into body fat, which is a more permanent form of energy storage. Eating a potato, or any other type of carbohydrate rich food, won't automatically make you fatter. You should, however, be careful of the topping you choose (for example, butter and sour cream are high in fats).

You have to regularly eat more energy than your body needs to put on weight. This is harder to do with high carbohydrate foods than high fat foods. Eating a diet high in carbohydrate (and also fibre) is likely to crowd fat out of the diet.

2.Food combining should be avoided - false
There are plenty of crash diets that are based on the belief that the human digestive system isn't capable of tackling a combination of foods or nutrients. Commonly, carbohydrates and proteins are said to 'clash', leading to digestive problems and weight gain. The opposite is often true. Foods eaten together can help the digestive system. For example, vitamin C in orange juice can increase iron absorption from a meal of iron containing foods, like chicken or beef. Very few foods are purely carbohydrate or purely protein, most are a mixture of both. The digestive system contains enzymes that are perfectly capable of breaking down the foods we eat. If a person ate only fruit, the body's carbohydrate enzymes and carriers for digestion and absorption would be busy while those for fat and protein would sit practically unused.

3. Breakfast should consist of fruit only - false
There is no evidence that limiting your breakfast solely to fruit has any health or weight loss benefits. Most fruits are not very high in complex carbohydrates, which the body needs after an all-night fast. They are a good source of fibre and vitamins. Cereal foods (especially wholegrain varieties) like bread, crumpets, muffins and breakfast cereals are a much better source of carbohydrates, to get you going in the morning.

4. There are some magical foods that cause weight loss - false
Some foods, such as grapefruit or kelp, are said to burn off body fat. This is not true. Dietary fibre comes closest to fulfilling this wish because it provides a feeling of 'fullness' with minimal kilojoules. High fibre foods such as fruit, vegetables, wholegrain breads and cereals, and legumes also tend to be low in fat.

5. Drinking while you are eating is fattening - false
The theory behind this misconception is that digestive juices and enzymes will be diluted by the fluid, resulting in slowed digestion and excess body fat. There is no scientific evidence to back this up. In fact, evidence suggests that drinking water with your meal actually speeds up digestion. Kilojoule-heavy drinks such as alcoholic beverages can be fattening if consumed in excess, but drinking them with meals doesn't make them more so. However, drinking alcohol with a fatty meal can increase body fat. Nevertheless, the only way you can put on weight is to consume more energy than you expend.

Regular eating pattern and Snacking
Data suggest that a regular pattern of eating with little variability in daily energy intake is associated with weight control and more successful weight loss (Tucker & Peterson, Obesity Research 2000). The type of pattern apears to be less important - there appears to be no direct weight control benefit between a 3 meals a day pattern and one with a greater number of smaller meals (assuming food choices are the same). An erratic pattern of eating (i.e high day to day variations in energy intakes) has been associated with higher energy intakes and body weight probably because it disrupts appropriate appetite regulation. Snacking by itself has little direct effect on energy balance provided the pattern is consistent and the snacks are not energy dense.

The key to weight loss
Suggestions for safe and effective weight loss include:
Don't crash diet; you'll most likely regain the lost weight within five years.
Aim for small, slow losses of around one kilogram per week or less.
Cut down on dietary fats, especially saturated fat.
Cut back on refined carbohydrates
Increase your intake of fresh fruit, vegetables and whole grain foods.
Consume less alcohol.
Eat less takeaway and snack foods.
Exercise for approximately 30 minutes at least a few times every week. Introduce more movement into your day - try to accumulate 30 minutes of walking daily.
Don't eliminate any one food group - choose from a wide range of foods every day instead and prefer 'whole' less processed foods.
Have a regular pattern of eating and stick to it
Many experts also suggest that having five to six small meals a day instead of three larger ones, and eating less at night and more during the day, is associated with a lower body mass index.

Where to get help
· Your doctor
· Dietitian

Things to remember
· Overweight and obesity are caused by eating more food than your body needs.
· Crash diets have promoted many unhealthy misconceptions about weight loss. In most cases the weight lost on crash diets is regained within five years.

Related articles:

Weight loss diets - background

Visceral fat

Article co-authored by Better Health Channel
(Australian -Victorian Government website)

Last Updated: July 2005