2. Factors which may indicate a genetic influence in fat loss response (i.e. parental body shape; early onset of overfatness; duration of effect) should be included in any pre-program screening.

3. It may be necessary in certain groups (i.e. the aged, pre-meno-pausal exercising females) to check the level of spontaneous physical activity being carried out outside a planned exercise regime and attempt to increase this through ‘incidental’ activity.

4. Individuals with a genetic predisposition to obesity may have difficulty limiting food intake and the taste for fatty foods.

5. Recognise the major gender differences in fat loss responsivity to both energy input restrictions and energy output and design fat loss programs accordingly.

6. Avoid severe restrictions of food intake or heavy exercise prescription in females as these may have a counter-productive effect on the biological propensity of females to conserve energy for reproduction.

7. Recognise the potential for excessive fat gains during and following pregnancy in some women and attempt to offer preventive prescriptions for this, particularly in those most likely to be at risk.

8. Avoid programming which involves unrealistic expectations about body image, particularly in females.

9. Extreme forms of body building with accompanying overeating disorders in men should be seen as the equivalent of anorexia in females—there are comparative body shape obsessions and distortions.

10. Programming should be modified to account for differences in responses that occur with ageing with both men and women, but particularly in post-menopausal women.

11. Monitor possible changes in eating patterns that occur with ageing, of which the client should be aware.

12. Use body fat and fat distribution measures such as BMI and waist-to-hip ratio cautiously in some racial groups (such as Pacific Islanders, Asian and Negroid women) for whom these measures are not necessarily appropriate.

13. Recognise racial differences in body shape and composition and the implications of this for healthy body weight and fat maintenance.

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Fat mass. As body fat levels increase so does RMR. Most of this is due to the increased FFM, but even at the same amounts of FFM, the person with the higher fat mass (FM) has a higher RMR. Similarly, as FM decreases, RMR will decrease and tend to ‘brake’ the reduction in body fat which might otherwise occur.

Age. Recent research estimates that RMR decreases at a rate of approximately 2 per cent per decade between the ages of 20 and 70 years. This reduction is accounted for primarily by decreases in FFM which is mostly due to reduced overall physical activity. However, at the same levels of FFM and FM, older people have a slightly lower RMR.

Gender. For a given body weight, females have a lower RMR than males due to a lower FFM to FM ratio. Females also have a slightly lower RMR than males independently of FFM, FM and age, most probably due to the effects of sex hormones on RMR. Several studies have shown that energy expenditure varies within the female menstrual cycle. During the preovulatory (progesterone) stage, RMR appears to be 6-15 per cent lower than during the pre-menstrual (oestrogen) stage. RMR may also be reduced in women taking progesterone-only oral contraceptives.

Genetics. FFM, FM, sex and age account for about 70-80 per cent of the differences in RMR between people. Other genetic factors account for some of the remaining differences. This suggests that RMR is at least partially genetically determined. These findings are supported by studies involving identical (monozygotic) and non-identical (dizygotic) twins which showed that identical twins are more alike with respect to RMR than non-identical twins.

Sympathetic nervous system (SNS) activity. The SNS is that part of the nervous system involved in generally speeding up the body’s responses, for example through increased heart rate, constriction of blood vessels and release of hormones such as adrenalin. The SNS also stimulates lipolysis resulting in the release of free fatty acids (FFA). The degree of SNS activity may have a small influence on RMR.

Ambient environmental temperature. When the environmental temperature is low, maintenance of normal body temperature at 37°C is an active process requiring extra energy. For this reason more energy needs to be expended in cold conditions than in warm. The cooling process (for example, sweating) is more energy efficient than the heating process (for example, shivering). The use of a sauna bath may result in fluid loss (and therefore weight loss), but not significant fat, or energy loss. Similarly, exercising while rugged up to increase sweating is only likely to have a short term effect on fluid loss and no extra effect on fat loss over and above the exercise. On the other hand exercising in the cool or cold, while only lightly dressed, would require that the body increase its energy use to maintain body temperature. Of course, this needs to be balanced by the injury protection benefits of warming up muscles before exercising.

Physical activity. One question which is often asked is whether physical activity has a carry-over effect on RMR? In the short term immediately after exercise, there is an excess post-exercise oxygen consumption (EPOC) which reflects an ongoing excess metabolic rate. The duration of EPOC is dependent on the duration and intensity of the exercise, but it may last for a few hours. In the longer term, the question of whether fit people have a higher RMR after the EPOC has disappeared (say 24 hours after an exercise bout), is less clear. A recent review of all the major work earned out in this area’ suggests that regular physical activity does have a positive effect on increasing RMR but this is mainly because of the relative increase in FFM in the body. The longer term benefit of regular exercise on metabolism is probably more related to changes in the respiratory exchange ratio (RER) than RMR.

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Janet grew up in a family whose clean-your-plate philosophy was largely responsible for her eventual size-14 figure. Over the Ik I years, she dieted time and again, sometimes shedding a few pounds. But she’d lie awake at night, feeling starved. Inevitably, she’d return to large meals and constant snacking. Over a lifetime of gaining, losing, and regaining, Janet watched herself hit a high of 164 pounds. Finally, at age 64, the Old Forge, New York, resident became determined to slim down. “It was either buy yet another new wardrobe or take off the weight,” she says.

Her first step was to drop her drastic dieting and go back to preparing and eating her regular foods. For Janet, that meant meals of steak, potatoes, and corn; or chicken, rice, and broccoli—both always served with a salad. The main difference was that she began to leave a little food on her plate at the end of every meal.

This trick helped Janet control her portion sizes. But she still craved snacks. So she tried drinking skim milk between meals as a way to take the edge off her hunger. “I like the taste of milk, and I knew from experience that drinking it made me feel full,” she explains. “Besides, the extra calcium is good for my bones.” She also ate an orange every night before going to bed, to keep her stomach full until morning and stave off the midnight munchies. Slowly but surely, the extra pounds came off—and have stayed off for 2 years.

Today, at age 66, Janet weighs 147 pounds and wears a size-10 dress. “Drinking milk is the easiest thing I’ve ever done to lose weight,” she says.

WINNING ACTION

Satisfy your hunger with skim milk. A cold 8-ounce glass of skim milk is not only filling but also healthy—a great source of bone-building calcium. If you aren’t a fan of skim milk, try 1 percent. It has a richer taste but each

serving still gets fewer than 30 percent of its calories from fat. If you’re a chocoholic, add 2 tablespoons of Her-shey’s Syrup for a fast chocolate fix with only 50 calories and no fat.

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