• There are a number of critical periods throughout life where gains and losses in body fat and body weight are likely to occur.

• Some of these are due to physiological causes, others to behaviour and/or periods of high stress, crisis or grief.

• Restrained eaters may be likely to gain more fat during periods of chronic stress, crisis or grief.

• Awareness of critical stages and actions that can be taken to resolve these may help prevent or reduce increases in body fatness.

Although the causes of obesity and overfatness are multi-factorial, the problem may be exacerbated at certain critical’ periods in life. These are generally associated with change, either in lifestyle, as a result of crises or increased levels of stress, or due to the natural physiological changes that occur with ageing. As some psychologists have pointed out, change is often associated with increased stress levels, even in some cases where these changes are positive. Stress, in turn, can be crucial for either increasing or decreasing body fat depending on the circumstances. There are periods that predominantly affect either males or females and others that are less gender specific. Some are potentially avoidable and others are an unavoidable function of the ongoing processes of growth and change. An awareness of at least some of these critical periods and the potential means of alleviating their effects is crucial to an understanding of long term body fat maintenance. Although the scientific evidence on some of the periods is limited, practical suggestions based on experience are discussed for each period.

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Fat. Fat is handled very differently by the body compared to the other nutrients. Body fat stores are large and not actively controlled and fat intake has no influence on its own use as a fuel (oxidation) and very little influence on appetite. Fat (from the diet or adipose tissue) is the energy buffer for the body in that it makes up the difference between what the body obtains from non-fat calories and what it needs to keep functioning. It is the last priority as a fuel. Fat is therefore not balanced at all and in a sense the body is ‘blind’ to fat, both in the diet and in the fat stores when it comes to balancing up its energy needs. Excess fat is therefore the most powerful dietary promoter of weight gain.

Energy balance and fat balance are essentially equivalent. This means that on a day when a person has eaten 200kcal more than they have burned, about 200kcal of dietary fat will be stored as body fat. If a person is 200kcal under, the body will pull about 200kcal of fat out of the fat stores to make up the deficit.

Table 5.1 shows how carbohydrate and protein intakes are fully balanced or regulated (suppress appetite and promote their own oxidation), alcohol intake is only half balanced (promotes its own oxidation only), and fat is not balanced at all. As originally proposed by Professor J-P. Flatt from the University of Massachusetts, a high-fat diet therefore tends to lead to a passive over-consumption of calories which may become chronic because of the weak or absent metabolic controls on fat balance.’

All this implies that a reduction of fat in the diet is all that is required for reducing body fat. There are certain advantages and disadvantages of this approach, as opposed to the old notion of calorie counting. Reducing fat, for example, doesn’t feel like ‘dieting’ and is therefore much easier than total food restriction. However, there is a perception that a low-carbohydrate diet is more effective because much of the weight lost is fluid which occurs relatively quickly. In a low-fat diet, the loss is slower but is more likely to come from fat than fluids. The low-fat approach also allows large volumes of food to be eaten with a minimum of restrictions, hence not resulting in the problems of hunger which occur with normal ‘diets’. In general, this whole approach leads us away from the traditional notion of calorie counting to one of ad libitum low-fat eating—a much more practical and effective approach to fat loss.

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She’s exaggerating, of course, but not by much. At one time, the 41-year-old consulting-firm director and mother of three carried 263 pounds on her 5-foot-2-inch frame. She blames the excess baggage on the sheer exhaustion of making repeated crosscountry trips. “When you’re that tired, you eat what’s convenient—and that often means unhealthy foods,” she says. “And once I’d blow it, I’d feel sick the whole trip. It sets up a cycle of bad eating.”

Finally, Rosanna wised up to her unhealthy ways. Temptation is greatest when you’re out of your routine,” she says. So she devised a plan for ensuring that she sticks with her healthy eating habits when she travels. “I pack an emergency food kit, using an insulated lunch bag that belonged to one of my kids,” she explains. “I fill it with cans of tuna, small cans of vegetables, canned snack packs of fruit that are for kids’ lunches (the portion sizes are perfect), fresh fruit, and bottled water. That way, I’m not a victim of airport food or late-night room service because it’s the only thing available.”

Today, a year later and 103 pounds lighter, Rosanna is happy, comfortable, and soaring with energy. She says that packing her emergency food kit is like brushing her teeth. “I won’t leave the house without doing either one,” she says. “They’re so much a part of me that I can’t avoid them.”

WINNING ACTION

Flying? Don’t forget your food. You don’t have to be a frequent flier like Rosanna to face the nutritional pitfalls of air travel. Your best bet is to prepare for your hunger.

Pack your carry-on bag with healthful snacks such as bagels, fresh or dried fruit, single-serving boxes of cereal, and nonfat or low-fat sliced cheese. Take some water, too. Airplane cabins are extremely dehydrating; during a 3-hour flight, you can lose more than a pint of water through your skin and by breathing.

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