By Meredith Beil
Approximately 50% of the Australian population are currently overweight or obese and the rates are rising. This extra weight that we are carrying is associated with greatly increased health risks, which not only shorten our lives, but also give us a poorer quality of life. The likelihood of having poor health and suffering with chronic debilitating diseases such as Type 2 diabetes and cardiovascular disease is greatly increased with increasing weight. On the positive side, weight loss of >5% for at least one year has been shown to have many significant health benefits, as well as improving self-esteem and energy levels, even if the resultant weight isn’t as low as the healthy weight range.
DEFINITIONS OF WEIGHT CATEGORIES
BMI (kg/m2) measurements are useful for population assessments of overweight and obesity levels, but not so useful on an individual basis due to differences in muscle mass: e.g. BMI readings of athletes are irrelevant. A more important determinant as an indicator of health risk is waist circumference. Health risks increase greatly with increasing waist size; which is a measure of abdominal fat mass. This adipose tissue is not just a store of energy but is a highly active tissue, which secretes many chemicals into the body that contribute to poor health.
WAIST MEASUREMENT CLASSIFICATIONS
Slight increase in health risks Substantial increase in health risks
Caucasian Asian All nationalities
MEN >94cm >90cm >102cm
WOMEN >80cm >80cm >88cm
OBESITY IN AUSTRALIA
The obesity epidemic is increasing across all sectors of our population. By the time we reach age 40 the majority of us are overweight or obese (>50% of women and >65% of men). Our children are also entering the obesity epidemic at an alarming rate with studies showing approximately 25% of Australian boys and girls in the overweight or obese categories.
HEALTH RISKS OF OBESITY
Stroke Heart Disease Type 2 Diabetes Cancer Osteoarthritis Sleep apnoea Hormone and Fertility problems Gall bladder disease Respiratory disease Gout
Medical research shows that a weight loss of 10% decreases diabetes related deaths by >30% and obesity related cancer deaths by at least 40%, while reducing blood pressure and improving cholesterol readings significantly.
ENERGY BALANCE AND PHYSICAL ACTIVITY
The reason our body weight changes relates to the equation of energy balance. If we consume more energy than we use we put on weight. Similarly, burn off more energy than the kilojoules we consume and we will lose weight. Physical activity is a major contributing factor that we can consciously modify.
ENERGY IN < ENERGY OUT = WEIGHT LOSS
Energy in : Energy out
Kilojoules from food and drinks : Physical activity (10-40%) food digestion (5-15%) & resting metabolism
Both sides of the equation need to be addressed: i.e. kilojoules consumed and energy used. Reducing kilojoules without adequate physical exercise will result in loss of muscle mass and a lowering of the body’s metabolism with greater weight gain long-term. Moderate to vigorous exercise for at least an hour a day is associated with long-term body fat reduction.
DIETARY APPROACHES TO WEIGHT LOSS
Changes in diet need to be maintained and research shows that overly restrictive diets and fad diets may have nutritional deficiencies, are unsustainable and often cause long-term weight gain. It is vital that any weight loss diet contains adequate nutrition for good health consistent with current dietary guidelines.
There are 3 main categories of weight loss diets:
reduced energy diets
low energy diets
very low energy diets
Reduced energy diets involve a reduction in energy intake of usually between 2000 and 4000 KJ per day. A sustainable weight loss of 0.5-1kg per week providing a significant weight loss over 1-2 years with the all important reduction in waist circumference is achievable. The most success in the long term with reduced energy diets is when fat intake is significantly reduced, which also allows for maintenance of nutritional requirements.
Low energy diets usually provide 4000 to 5000 KJ per day, often using meal replacements such as shakes, soups or bars and/or pre-packaged portion controlled meals. They have been shown to reduce weight by an average of 8% over 3-6 months. Over the longer term of 3.5 to 4 years the average maintenance of weight loss was shown to be 4% less than the starting weight.
Very low energy diets provide 1700 to 3300 KJ daily, using vitamin and mineral fortified liquid meals as generally the sole nutritional source. This is only recommended for the morbidly obese or when rapid weight loss is medically required. These diets obviously provide greater short-term weight loss but research shows that over a period of 12 months, weight regain is similar to the low energy diets.
Neither low energy nor very low energy diets should be considered for continuous
Long-term treatment unless under the close supervision of a medical professional.
OTHER DIETARY FACTORS
Reducing dietary fat or dietary carbohydrate without an increase in total energy input does not reduce weight.
Low carbohydrate diets do produce a quicker weight loss due to loss of the muscles’ carbohydrate stores (not body fat) along with associated stored water. This water and glycogen is quickly replaced in the muscles once carbohydrate is reintroduced. Low carbohydrate diets have been shown to be ineffective long-term and “thankfully are now totally and utterly debunked” according to Dr Tim Crowe, nutrition lecturer from Deakin University.
Although in theory low GI diets could benefit weight control by promoting feelings of fullness and promoting usage of fat; the medical research to date shows no difference in weight loss when comparing high GI with low GI diets.
Energy density of food does have an impact on the amount of kilojoules we consume, as we prefer to eat a constant weight of food each day; another important reason to consume more fibre, fruit and vegetables which all have lower energy densities than high fat and/or high sugar foods.
MEDICATIONS AND SURGICAL PROCEDURES
We do have scientific evidence that medications available from your pharmacist or doctor are effective, however a review of a large number of over the counter supplements marketed for weight loss showed that none of the supplements were effective and/or safe. Surgical procedures, of which lap banding is the most common in Australia, has proven to be effective in maintaining weight loss, as well as reducing mortality from causes positively associated with obesity.
SUCCESSFUL WEIGHT LOSS
Successful loss of weight is weight that is kept off long-term with lifelong changes to diet and lifestyle.
Successful weight loss is associated with:
Long-term support with an accredited practising dietician, doctor, other health professional or support group is also positively associated with prevention of weight regain through the maintenance of behaviour modification. It is this long-term weight loss that will have the greatest impact on improving health outcomes and thus maintaining a healthier weight should be viewed as a life-long strategy.