Nutrition - Free Fitness Library
Diet failure... why can't I lose weight?
By Anita Bean BSc
There are many myths surrounding metabolism, dieting and weight management.
Study after study has demonstrated that an inability to lose weight
is very seldom due to a metabolic defect. So, how can ardent dieters
still remain fat? Why are those last few pounds so difficult to shift?
Well, clearly, this is impossible. An alternative explanation can usually
be found by delving more closely into the dieter's daily eating habits,
lifestyle and psychology. Keeping a detailed, honest, weighed food diary,
ideally for seven days, can reveal many truths.
1. Underestimating Food Intake
Researchers say that many 'resistant' dieters underestimate their food intake. Numerous studies have found that such people consciously or subconsciously underestimate how much they eat.
An honest food diary often reveals a person's true eating habits. Here are some real-life examples from my files:
* Diary 1 (Elaine)
In addition to her normal 'diet' meals:
4.30pm - Slice of bread and butter; handful of crisps, slice of cheese
while preparing children's' tea
5.30pm - Half fish finger; handful of crisps; half pot shots yoghurt
while clearing children's' tea
6.30pm - Spoonful of cheese sauce; several chips; slice of cheese while
preparing supper
8.30pm - Glass of Baileys and a couple of chocolate brazils while watching
TV
Extra calories = 990 kcal.
Daily total = 2190 kcal
* Diary 2 (Dawn)
When asked to weigh her food, portion sizes came up much bigger than
she ever realised:
8.30am - Bowl of muesli (140g/5oz) with 1/3 pint semi-skimmed milk
12.30pm - 2 slices of bread (70g/2.5oz each) with margarine and slice
of cheese (75g/3oz)
7.00pm - Pork chop (200g/7oz); potato (150g/5oz); vegetables; Rice pudding
(200g/7oz) with spoonful of jam; Glass of red wine (200ml/ 1/3 pint)
Daily total - 2200kcal.
In a study carried out by researchers from the University of Ulster and the Dunn Clinical Nutrition Centre, 16 men and 16 women kept a 7 day weighed food diary while their total energy expenditure was simultaneously measured using a highly accurate method called the doubly-labelled water method. There was little difference in energy expenditure but there was a wide variation in reported energy intakes. This mismatch between energy expenditure and apparent low intakes in some people could only be explained by under-reporting of food intake and not, say the researchers, to any defect in energy metabolism.
2. Weekend Splurging
Many dieters restrict their food intake during the week then relax restraint at the weekend, celebrating their dieting efforts by splurging on high fat 'treats' - often aided by alcohol. It is very common to see women stick to a rigid diet from Monday to Friday, perhaps eating little more that 1000 - 1200 kcal per day then give way to their mounting hunger by Friday night, often getting through the region of 3000 kcal a day. Despite their weekday dieting efforts their total weekly calorie intake ends up exactly the same as if they had eaten their normal maintenance calorie each day (i.e. not dieted).
It is hardly surprising that such dieters fail to stick to their diet over the weekend. By Friday evening their glycogen (carbohydrate) stores are very depleted, they feel fatigued, hungry and so they permit themselves a large meal.
Guilt after the weekend splurge brings on renewed resolve to diet more strictly during the coming week. This, again, is followed by hunger, increased appetite, over-eating, guilt and so the vicious circle continues. It's easy to see how the weekday dieter becomes more and more frustrated. She feels as if she is always on a diet yet not losing any weight.
3. Daytime Starving/Evening Bingeing
It is common to find that many dieters eat very little during the day, skipping breakfast and surviving only on snacks. Daytime starvation leads to depleted glycogen stores which inevitably leads to exaggerated hunger by the evening and consequent over-eating.
Eating most of your food in the evening has a significant effect on your metabolism.
A study published in 1993 in the American Journal of Clinical Nutrition found that if you eat in the early part of the day you burn off more calories by a process called dietary induced thermogenisis (DIT) which the energy used up as a result of digesting and absorbing a meal. Volunteers were given a 544 kcal meal either at 9am, 5pm or 1am. DIT raised calorie expenditure by 16%, 13.5% and 11% respectively. Thus, eating late at night burns off fewer calories than eating during the daytime.
4. Evening Nibbling
A food diary may reveal that a dieter's evening meal extends to an all-night sitting. It's easy to discount snacks and nibbles consumed mindlessly in front of the television. Many dieters will snack in the evening through boredom, misery, anger or other emotional reasons without consciously realising or admitting how much they have eaten. Kathy, mother of two young children, claimed to be on a strict diet and unable to lose weight. When I asked her to keep a food diary we discovered that she was nibbling an extra 500-1000kcal most evenings when the children had gone to bed and she had some time to herself. These were often accounted for by half a dozen chocolate biscuits, a couple of packets of crisps with a large gin and tonic, or a toblerone treat. Together, we worked out a coping strategy.
5. Setting an Unrealistic Goal
It's a very common mistake to aim for an unrealistically low body weight. One theory is that the body attempts to regulate it's weight close to a genetically determined 'set point'. The body uses a variety of adaptive mechanisms to maintain it's weight and body fat at a certain level. Studies have shown that when people are underfed the body reduces it's spontaneous physical activity, it's thermic response to food (DIT) and, temporarily, it's BMR in response to what the body perceives as imminent starvation. Research by Dr Stuknard in the USA suggests that everyone's body is programmed to be at a certain weight. So, people who are constantly striving to attain a low body weight may be fighting a losing battle with their genes as well as putting their health at risk and creating unnecessary psychological stress.
6. Dieting Mentally
There is evidence that there is a psychological difference between dieters and non-dieters. In dieters and weight conscious people, the normal regulation of food intake becomes undermined as normal appetite and hunger cues are ignored. This leads to periods of restraint and semi starvation followed by over indulgence and guilt followed by restraint and so on.
Dieters usually live by a set of rules, centred around allowed foods and banned ('naughty') foods. For example, in one US study, dieters were given two apples, (100 kcal) or 2 squares of chocolate (100 kcal). Those who ate the chocolate perceived themselves to be breaking their diet and went on to overindulge at the subsequent meal. Those who ate the apples continued with their diet.
At the University of Toronto, dieters and non-dieters were given high calorie milkshake followed by free access to ice-cream. The dieters actually went on to eat more ice-cream than the non-dieters, a phenomenon known as 'counter regulation'. They failed to compensate for the calorie pre-load.
More recently, Dr Barbara Rolls at Penn State University demonstrated that weight worriers appear to lack a kind of internal calorie counter possessed by normal people who don't worry about their weight. When given a yoghurt half an hour before lunch, those who worried about their weight ate more for lunch than the free and easy people. It appears that such dieters have poor appetite control and are unable to compensate for previous food intake.
It has been shown that habitual dieters tend to have a more emotional personality than those who are not weight preoccupied. Psychologists say that they tend to be more obsessive and have more problems concentrating.
Checklist
* Make a food dairy for a week, writing down the weight of everything you normally eat and drink. This helps you become aware of your true eating pattern.
* Do not skip meals or starve yourself during the day.
* Plan regular meals and snacks throughout the day, thereby eliminating excessive hunger, satisfying appetite, facilitating efficient glycogen refuelling, improving energy levels and health.
* Set yourself a realistic weight goal that is right for your body type.
* Avoid weekday dieting and weekend splurging. Aim to eat about the same amount of food each day and don't worry if you occasionally overdo it.
* Remember there are no banned foods; all foods are allowed.
* Do not set yourself rigid eating and exercising rules. Be flexible and never feel guilty if you over indulge or miss an exercise session.
* Examine your feelings and emotions when you eat. Food should not
be used as a shield for emotional problems. Solve these with the help
of a trained counsellor or an eating disorder specialist.
Conclusion
An inability to shift those last few pounds has no metabolic cause. It is a myth that dieting slows down your metabolism or makes you burn calories more slowly.
Most resistant dieters simply underestimate their food intake. This
may be due to subconscious eating habits, such as snacking, nibbling
or regularly eating large portions. Dieters often stick to a rigid set
of rules for the majority of the day or week, only to break them in
the evening or weekend. Thus, they feel that they are on a diet most
of the time but, in fact, any calorie deficit is soon compensated for
by a surplus calorie intake at other times.
Anita Bean BSc is a nutrition consultant with over 11 years experience of advising sports people, national teams and fitness participants. Winner of The Exercise Association's 1995 Award for Special Achievement, she is the co-director of P&A Sports Nutrition. Anita writes regularly for many fitness, health and women's magazines.
For more details, send an SAE to P&A Sports Nutrition, 26 West St, Epsom, Surrey KT18 7RJ.