Dieters in this study ate slightly more (on average 2234 cal/day) than did the non-dieters (on average 2066 cal/day).The dieters also ate significantly more snacks and ate
more frequently than did the non-dieters.
Many studies have found that across a variety of conditions, dieters typically eat more
than do non-dieters. It appears that maintenance of control of eating in dieters is rare.
Numerous laboratory studies have revealed a variety of “diet disrupters” or triggers of
overeating. These include anxiety, distress, depression, positive emotion, alcohol, actual
or anticipated consumption of a “diet-breaking” food (e.g., a milkshake), or the mere
exposure to the smell and thoughts of such foods. Many of the factors that trigger
overeating in dieters typically inhibit eating in non-dieters. For example, non-dieters eat
less than they would otherwise if they are anxious, distressed, or depressed. Research
shows that people are good at maintaining their diets only as long as they are not exposed
to any diet disrupting triggers. Unfortunately, in the real world the dieter is constantly
subject to these, and is therefore likely to overeat frequently.
The link between dieting and binge eating
Dieting has been identified as a risk factor in the development of eating disorders and in
particular, binge eating. This is best illustrated by a classic study documenting the effects
of starvation at the University of Minnesota in the 1940s. Thirty-six normal,
psychologically healthy males volunteered to be in the research study as an alternative to
active military service. They were put on a strict starvation diet with the goal of reducing
their body weight by about 25 per cent. Soon after being on the starvation diet, the men
started to exhibit the psychological and physiological effects of starvation—symptoms
strikingly similar to those experienced by people with eating disorders. Several of the
men lost control of their eating and appeared to experience bulimic episodes. Both during
the re-feeding phase, when access to food was unlimited, and after the men were weight restored,
several of them continued to experience extreme hunger and would eat huge
quantities of food without feeling satisfied. This study provides compelling evidence that
extreme food deprivation can lead to excessive eating and, in some individuals, to binge
eating.
However, it is not necessary to experience extreme physiological deprivation for
overeating and extreme hunger to occur. Evidence shows that psychological deprivation,
induced by short periods of caloric restriction is enough to trigger overeating and increase
hunger. In a recent study, a group of young, healthy non-dieters were placed on a four week
intermittent dieting schedule. Participants followed a strict calorie-reduced diet
(below 600 cal/day) on four days of the week and were able to eat without restrictions on
the remaining three days of the week. The researchers found that the participants reported
that the tendency to overeat, as well as the amount of calories they consumed, were
significantly increased from the baseline on the days that participants were allowed
unlimited access to food. The participants in this study also experienced increasing irritability and fatigue, worsening of mood and impaired concentration over the course of
the four-week period, all common amongst dieters. After the four weeks, they did not
experience a substantial weight loss, suggesting that the psychological deprivation
inherent in dieting is a significant factor leading to episodes of overeating. In fact,
longitudinal studies of weight fluctuations in dieters and non-dieters show that chronic
dieters do not usually lose weight over time, despite actively attempting to do so.
Self-presentation or cognitive distortion
So why do people believe that dieters eat less than non-dieters do? Well, presumably, the
easiest way to lose weight is to eat less, and the expectation is that dieters should eat less
because this is the best way to achieve their goal. Dieters, themselves, are motivated to
think they are eating less or perhaps, to present themselves to others as eating minimally.
In this way, they are succeeding at their socially acceptable goal: to be a good dieter.
Research has shown that dieters significantly under-report what they have eaten—they
tend to believe that they eaten much less than they actually have. In comparison, nondieters
tend to be very accurate at reporting the amount they have eaten. This and similar
findings may represent a cognitive distortion, functioning to protect the dieter’s selfesteem,
which is more heavily dependent on weight and shape than that of the non-dieter.
It is also possible that the dieter is motivated to under-report consumption to others, as
eating minimally is a socially desirable goal.
Adherence to dietary rules: when do dieters eat less?
When dieters come into the laboratory and are presented with an opportunity to eat as
much as they like in the guise of a bogus “taste perception task,” they typically eat less
than do non-dieters. But, this is true only when no disinhibitory triggers are presented or
manipulated. It would seem that dietary restraint is quite tenuous and that virtually
anything can induce dieters to break their diets.
A factor that induces “normal” eating (i.e., eating comparable to that of non-dieters) and
even decreased eating (i.e., eating less than non-dieters) in dieters is an increase in the
dieter’s self-awareness. Increased self-awareness at either the private level (i.e., increased
consciousness about what they are eating) or at the public level (i.e., increased awareness
that others are monitoring what they are eating) promotes adherence to the diet and
suppresses eating in dieters. Given the laboratory research, one would expect to see that
in naturalistic studies, dieters’ patterns of food intake would be characterized by
alternating periods of restriction and overeating. Contrary to these expectations, several
naturalistic investigations have found that dieters report eating less than non-dieters.
However, when we examine the methodology of these studies, a number of problems
emerge. The majority of these studies must rely on the self-report intake using dietary self-monitoring forms or food diaries. The validity of a dieter’s self-report of intake is
questionable given the evidence that dieters to tend to under-report their food intake.
Self-monitoring may also increase self-awareness, a factor shown to suppress eating in
dieters.
If chronic dieters were truly eating less than non-dieters, it would seem reasonable to
expect that they would also weigh less. However, many studies consistently find that
dieters weigh significantly more than do non-dieters, and that they do not lose weight
over time. This is further evidence that dieters may actually eat more than they report.
Given the evidence that dieting leads to overeating or bingeing, it is possible that the
consumption of such excess calories is manifested in an increased body weight in
dieters—an unfortunate, and ironic, consequence of trying to lose weight. Many people
who have dieted on and off for many years can look back at a picture of themselves when
they first started to try and diet and wonder why they ever went on the diet in the first
place, as over the years dieting has pushed up their weight.
What prevents dieters from consistently eating less?
What prevents dieters from achieving their goal of consistent caloric restriction? One
explanation for the association between dieting and overeating and for the proposal that
dieting may lead to bingeing is that dieting involves substituting the cognitive regulation
of eating for physiological control, in order to override the body’s natural defence of
weight. Cognitive regulation of eating is problematic because it is vulnerable to
disruption by conflicting cognitions and emotional factors. In addition, ignoring the
physical sensations of hunger and satiety in favour of a cognitive diet program leaves one
lacking a mechanism to stop intake if and when cognitive regulation fails. Other
mechanisms of diet failure that have been proposed include pressures from physiological
and psychological deprivation. Short-term physiological deprivation from periods of
restriction could increase vulnerability to episodes of overeating. For example,
physiological indices suggest that dieters may be “hungrier” than non-dieters. The most
probable mechanism is a complex one that encompasses a number of factors, including
cognitive restraint or psychological deprivation combined with cognitive, emotional and
situational pressures. This conflict between physiological and psychological cues and
internal and external forces in dieters is one specific example of a more general
phenomenon: the inhibition of a motivated behaviour typically leads to excess—the
opposite of the intended suppression.
The non-dieting alternative
In conclusion, dieting does not seem to produce reduced food intake. Dieters appear to be
able to adhere to dietary rules for only a transitory period of time, at which point, inhibition is lifted by a diet-breaking trigger. This could be caused by almost anything—
from a fight with a friend, to being given a piece of birthday cake at a party. For the most
part, dieters are not able to meet their goal of eating minimally.
Alternatives to dieting have been described in various ways as “normal eating,” “antidieting,”
and “undieting.” All of these approaches advocate several measures: (1) Giving
up dieting and restriction of intake. These programs advocate “normalizing” eating with
the goal of controlling eating by hunger and satiety, rather than cognitive and external
factors. The elimination of the concept of “forbidden” foods also eliminates the
psychological frustration associated with dieting. (2) Getting rid of the dieting mentality.
If there is no diet, there is no opportunity for failing at it, and thus subsequent self-derogation
is averted. (3) Working on accepting or tolerating the body at whatever its
size. This frees up a lot of energy to work on other aspects of the self from which the
dieter can derive esteem and satisfaction and suggests a better area for making those New
Year’s resolutions.