Ioannis Ioakimidis

Decelerated and linear eaters: effect of eating rate on food intake and satiety.

Women were divided into those eating at a decelerated or linear rate. Eating rate was then experimentally increased or decreased by asking the women to adapt their rate of eating to curves presented on a computer screen and the effect on food intake and satiety was studied. Decelerated eaters were unable to eat at an increased rate, but ate the same amount of food when eating at a decreased rate as during the control condition. Linear eaters ate more food when eating at an increased rate, but less food when eating at a decreased rate. Decelerated eaters estimated their level of satiety lower when eating at an increased rate but similar to the control condition when eating at a decreased rate. Linear eaters estimated their level of satiety similar to the control level despite eating more food at an increased rate and higher despite eating less food at a decreased rate. The cumulative satiety curve was fitted to a sigmoid curve both in decelerated and linear eater under all conditions. Linear eaters rated their desire to eat and estimated their prospective intake lower than decelerated eaters and scored higher on a scale for restrained eating. It is suggested that linear eaters have difficulty maintaining their intake when eating rate is dissociated from its baseline level and that this puts them at risk of developing disordered eating. It is also suggested that feedback on eating rate can be used as an intervention to treat eating disorders.

A method for the control of eating rate: a potential intervention in eating disorders.

A method for the control of eating rate gave subjects feedback from a computer screen on how much and at what rate to eat during a meal. The method also allowed us to record the development of satiety during the meal. Linear eaters—that is, women selected for eating at an approximately constant rate—underate when challenged to eat at a lower rate and overate when challenged to eat at a higher rate, thereby modeling the eating behavior of patients with anorexia nervosa and binge eating disorder, respectively. In both cases, the women’s postmeal perception of satiety mimicked that of the respective patient group. The results provide support for the notion that linear eaters have the capacity to exhibit disordered eating.

Cause and treatment of anorexia nervosa

The hypothesis that eating disorders are caused by an antecedent mental disorder, presently believed to be an obsessive compulsive disorder, has been clinically implemented during many years but has not improved treatment outcome. Alternatively, eating disorders are eating disorders and the symptoms of anorexic patients and probably bulimic patients as well, are epiphenomena which emerge as a consequence of starvation. This hypothesis is supported by the observations of the effects of a 6 month long period of semi-starvation on healthy human volunteers, which demonstrated not only the emergence of psychiatric symptoms but also the reduction in eating rate which is typical of anorexia nervosa patients. On this framework training anorexic patients how to eat may be a useful intervention. We report that anorexic patients, either with a body mass index<14 or >15.5 display the same pattern of eating behavior, with a low level of intake, a slow eating rate and a high level of satiety. They also have the same, high level of psychiatric symptoms, including obsessive compulsive symptoms. Training patients to eat more food at a progressively higher rate reverses these symptoms and patients remain free of symptoms during an extended period of follow-up. It is suggested that the pattern of eating behavior mediates between the starved condition and the psychopathology of anorexia nervosa.

Obesity and the brain

The world-wide increase in obesity has markedly stimulated research on the possibility that its cause can be found the brain. However, this research has produced little that can be used to treat obesity. The reason for the limited success of this approach may be that it relies on the hypothesis that the brain controls behavior. We suggest that this hypothesis is an artefact of the powerful tools used in behavioral neuroscience and that the brain has a permissive rather than causal role in eating behavior. Drugs affecting brain function are largely ineffective in treating obesity and may remain ineffective. Instead, we hypothesize that humans need external support to control body weight because they have evolved to pay a high physical price for food and are able to eat large amounts of food without constraints when that price is minimal. Two randomized controlled trials verify the hypothesis that support on how to eat normally and how to feel a normal level of fullness by use of on-line, real time feedback on a computer screen enables under- as well as overweight patients to adjust their eating behavior and improve their health.

Linear eaters turned decelerated: Reduction of a risk for disordered eating?

It has been suggested that restrained eating is a cognitive strategy that an individual uses for control of food intake. If losing control, the restrained eater enters a state of disinhibition and is therefore thought to be at risk for developing eating disorders and obesity. Restrained eaters eat at a constant rate and can therefore also be referred to as linear eaters. Here, we have tested the hypothesis that restrained eating is a state that can be modified by teaching linear eaters to eat at a decelerated rate. Seventeen female linear eaters scored high on a scale for restrained eating. When challenged to eat at an increased rate, a test of disinhibition, the women overate by 16% on average. The women then practiced eating at a decelerated rate by use of feedback from a training curve displayed on a computer screen during the meals. The training occurred three times each week and lasted eight weeks. When re-tested in the absence of feedback, the women ate at a decelerated rate, they did not overeat in the test of disinhibition and they scored lower on the scale for restrained eating. It is suggested that restrained eating is a state that can be reduced by training.

How eating affects mood

IOAKIMIDIS I, M. ZANDIAN, F. ULBL, C. BERGH, M LEON, AND P. SÖDERSTEN. How eating affects mood. PHYSIOL BEHAV 2011 (000) 000-000. We hypothesize that the changes in mood that are associated with eating disorders are caused by a change in eating behavior. When food is in short supply, the rhythm of the neural network for eating, including orbitofrontal cortex and brainstem, slows down and we suggest that this type of neural activity activates a partially overlapping neural network for mood, including dorsal raphe serotonin projections to the orbitofrontal and prefrontal cortex. As a consequence, people who restrict the amount of food that they consume, either by choice or by their limited access to food, become preoccupied with food and food-related behavior. Most eating disorders emerge from a history of dietary restriction and we suggest that disordered eating consequent upon food restriction produces the altered mental state of patients with eating disorders. Based on the present hypothesis, eating disorders are not the result of a primary mental disorder. Rather, this notion suggests that the patients should be treated by learning to eat an appropriate amount of food at an appropriate rate.

Description of chewing and food intake over the course of a meal

While the average frequency of chewing and food intake have been reported before, a detailed description of the pattern of chewing and the cumulative intake of food over the course of a meal have not. In order to achieve this goal, video recording of the maxillary-mandibular region of women eating food from a plate was synchronized with video recording of the plate and computer recording of the weight-loss of the plate. Video recording of chewing correlated strongly with chewing identified by magnetic tracking of jaw displacement in a test with chewing gum at three different frequencies, thus ensuring the validity of video recording of chewing. Weight-loss data were corrected by convolution algorithms, validated against human correction, using sliding window filtering to correct errors with video events as reference points. By use of this method, women ate on average 264 g of food over 114 min, they took an average of 51 mouthfuls during the meal and displayed on average 794 chews with 15 chews per chewing sequence. The number of mouthfuls decreased and the duration of the pauses after each mouthful increased in the middle of the meal and these measures were then restored. The ratio between chewing sequences and subsequent pauses remained stable although the weight of each mouthful decreased by the end of the meal, a measure that is hypothesized to be reflected in a decelerated speed of eating. The method allows this hypothesis to be tested and its implication for clinical intervention to be examined.

Children eat their school lunch too quickly: an exploratory study of the effect on food intake

BackgroundSpeed of eating, an important aspect of eating behaviour, has recently been related to loss of control of food intake and obesity. Very little time is allocated for lunch at school and thus children may consume food more quickly and food intake may therefore be affected. Study 1 measured the time spent eating lunch in a large group of students eating together for school meals. Study 2 measured the speed of eating and the amount of food eaten in individual school children during normal school lunches and then examined the effect of experimentally increasing or decreasing the speed of eating on total food intake.MethodsThe time spent eating lunch was measured with a stop watch in 100 children in secondary school. A more detailed study of eating behaviour was then undertaken in 30 secondary school children (18 girls). The amount of food eaten at lunch was recorded by a hidden scale when the children ate amongst their peers and by a scale connected to a computer when they ate individually. When eating individually, feedback on how quickly to eat was visible on the computer screen. The speed of eating could therefore be increased or decreased experimentally using this visual feedback and the total amount of food eaten measured.ResultsIn general, the children spent very little time eating their lunch. The 100 children in Study 1 spent on average (SD) just 7 (0.8) minutes eating lunch. The girls in Study 2 consumed their lunch in 5.6 (1.2) minutes and the boys ate theirs in only 6.8 (1.3) minutes. Eating with peers markedly distorted the amount of food eaten for lunch; only two girls and one boy maintained their food intake at the level observed when the children ate individually without external influences (258 (38) g in girls and 289 (73) g in boys). Nine girls ate on average 33% less food and seven girls ate 23% more food whilst the remaining boys ate 26% more food. The average speed of eating during school lunches amongst groups increased to 183 (53)% in the girls and to 166 (47)% in the boys compared to the speed of eating in the unrestricted condition. These apparent changes in food intake during school lunches could be replicated by experimentally increasing the speed of eating when the children were eating individually.ConclusionsIf insufficient time is allocated for consuming school lunches, compensatory increased speed of eating puts children at risk of losing control over food intake and in many cases over-eating. Public health initiatives to increase the time available for school meals might prove a relatively easy way to reduce excess food intake at school and enable children to eat more healthily.

A sex difference in the response to fasting

We determined whether women and men would alter their pattern of food intake after they had deprived themselves of food. We found that women consumed 12% less food after fasting and that men ate 28% more food after fasting. Serving more food on the test day did not increase food intake of women. Women, who ate at a nearly constant rate (linear eaters), consumed less food than those eating at an initially high speed which decreased over the course of the meal (decelerated eaters). Women decreased their food intake after fasting as their eating pattern became more linear. After fasting, men increased their food intake, and the rate at which they ate became more decelerated. Food intake of both women and men was normalized after fasting by providing feedback that encouraged them to eat according to the pattern they showed in the non-fasted condition. The results support the hypothesis that linear eating, and the dieting that elicits linear eating, are risk factors for the development of the abnormal linear eating pattern that characterizes patients with anorexia nervosa. The data also provide additional support for the use of behavioral feedback to normalize the pattern of eating for individuals who have difficulty maintaining their body weight.

Food intake and chewing in women

The frequency and weight of food removed from a plate and placed in the mouth was recorded by computer and synchronized with the pattern of chewing recorded by video filming of the maxillary-mandibular region in women selected for eating with a decelerating speed (decelerated eaters) or a nearly constant speed (linear eaters). Because linear eaters are at risk of developing disorders of food intake, body weight and mood, detailed study of eating behavior is clinically important. Although the pattern of chewing was similar in both groups, the decelerated eaters took fewer mouthfuls, which weighed less, by the end of the meal. Linear eaters ate the same amount of food throughout the meal. The rate of chewing a piece of chewing gum was lower than the rate of chewing food in both groups and lower in linear eaters than in decelerated eaters. The chewing gum chewing frequency correlated with the initial speed of eating food, which was lower in linear than in decelerated eaters. The neural network of chewing is well studied, engaging dorsal raphe serotonin neurons which project to orbito- and prefrontal cortex, whose activity, if experimentally changed, produces change in mood which mimic those produced by changes in chewing and parallel the changes in mood of patients with eating disorders. This detailed behavioral description of women at risk of developing disordered eating is the first step for integrating brain function and ingestive behavior in both healthy women and patients.