01.10.2015 Nutrition

Why Do We Overeat?

Before you launch into another doomed diet, Peter Dingle PhD suggests simple steps like keeping a food mood diary makes much more sense

I had a friend a long time ago who used to seesaw with her weight many times over the year. Whenever she got depressed or upset she would eat a lot of rich, high calorie foods that gave her some instant pleasure. Her favourites were chocolate, and Milo by the spoonful, straight from the can. Despite her reasons for binge eating, it didn't bring any happiness and in fact contributed significantly to her problem. We need to deal with the beliefs that underlie the undesirable eating patterns as part of any dietary program.

Examining emotions and habits during a weight loss journey gives an insight as to why people overeat or have a hard time maintaining weight after losing it. The reasons given for overeating and excess weight gain often have similar root causes including boredom, emotional instability and stress. Some of these I have already covered but the potential list is pretty long.

The major reasons for overeating include and our appetite include:

BusynessTime of day (energy levels)MoodNervousStressBoredomLow self esteemHormonal fluctuationsHungerPeer/social pressureRoutine/habitMedia and advertisingLow price/convenienceMental stimulationToo busyFeeling UnlovedAnxious or restlessHappyAngry or jealousTiredDisappointed or rejectedDepressed EmotionalAvailability

Or if there are real food cravings, it may require some mineral or nutritional supplementation. For example, some sugar cravings can be significantly reduced with chromium or vanadium supplementation. Sometimes more protein-rich foods need to be eaten.

Let's look at some of the main reasons

Busyness and stress are often the underlying factors why we put on weight. One way or another it prevents us from doing what we need and know we should be doing. Too busy to exercise, too busy to eat properly or buy the right food, too busy to take the time for ourselves, too busy. Woman are often so busy with looking after the family they constantly justify another little treat and poor eating to get them through another day, while both men and women often become too busy around their careers. Taking a bit more time for ourselves and focusing on our health and healthy eating can make a big difference to our lives.

Emotional weight gain can be a major problem and explains why any weight control program needs a lot of emotional support. Too much weight on the mind can put weight on the body. In a study of eating disorders in girls in the 7th to 10th grades, which also applies to us as we age, many reported an inability to distinguish between emotional feelings and hunger. Some of these girls were unable to distinguish between being scared, angry and hungry and lumped all of these conditions together, which led them to overeat whenever they had an emotional feeling. This is no wonder if you look at how we use foods as rewards and distracters as we grow up. Often when we are feeling upset or anxious we use food as a substitute.

Energy lows can be a major appetite trigger, either directly or indirectly, in the amount of energy you have. If you understand your daily energy cycles you can avoid many food cravings and not confuse your levels of energy with poor eating habits. Remember, they are just habits. Most binge eating, for example, occurs in late afternoon and late evening when energy levels are low. At this low energy time, you are also more likely to feel in a low mood, so the food further acts as an energy catalyst to get you out of that mood. But this solution is only a short-term mood changer and often has a negative energy and emotional rebound effect. In support of this, one study of dieters found that the average time at which relapse occurred was late afternoon at 4.34 pm, about four hours after their last meal when they were moderately hungry and their energy levels were low. Most cases of temptation and relapse were characterised by upset including anger and by depression or tiredness.

Depression and diet link

On the other side of the coin, research is increasingly showing that how we feel is also affected by what we eat. Research shows links between depression and nutritional deficiencies. The research also shows that the deficiencies do not have to be excessive to depress the mood. So it can become a vicious circle of food-mood-food.

Dieting and food restriction can also play havoc with our moods. In a review of dieters, the research concluded that negative moods, particularly depression, increased eating amongst the dieters. In another study of people who were at least 30% overweight and ate only a fasting supplement of 420 calories per day over a 10 week period, they most commonly violated their diets in the second month at a time when they were feeling fatigued. Using a brain imaging machine, when you fast or deprive yourself of food (as in a diet), your brain sees high calorie foods as being far more pleasurable. The cravings and temptation to eat unhealthily will be far more intense. This is what they found in the short term, at least. It appears the orbifrontal cortex is responsible for how the brain perceives the "value" of a food - or how pleasurable it will be to eat.

There is no doubt the negative effects low moods and energy have on weight management. For many people, when these two are low up goes the weight. Fortunately, for most people, physical activity is the most effective way to raise energy and reduce tension. It produces rapid and reliable results that can change moods immediately.

Scientific evidence overwhelming shows that even moderate physical activity has the ability to increase your energy, unlike the energy drinks which actually make you feel more drained. In an experiment where one group was exercising by walking and a control group sat quietly reading over materials, there was a significant and unmistakable change in mood with the walking group. Research has highlighted that 15 minutes of walking produces slightly more energy than five minutes but even five minutes of brisk walking has a significant effect. After just a 10 minute brisk walk there were still statistically significant effects 60 minutes later and a weak energy increase was still evident after 120 minutes. A brisk walk therefore energises the person for somewhere between 30 to 90 minutes afterward.

Reasons to snack

In a study on unhealthy snacking, researchers identified six distinct motives for snacking including opportunity-induced eating, coping with negative emotions, enjoying a special occasion, rewarding oneself, social pressure, and gaining energy. Sound familiar? While enjoying a special occasion and opportunity-induced eating were most important, for all reasons except to enjoy a special occasion, younger people reported a higher score. Women indicated a higher score than men on coping with negative emotions, enjoying a special occasion and gaining energy. People who diet to a stronger extent reported a higher score for snacking because of social pressure, to reward oneself and to cope with negative emotions, with the latter also related to a higher BMI.

Effect of movies

Other studies have also made a link between emotions and snacking. One study showed moviegoers watching tearjerkers ate between 28% and 55% more popcorn, both in the lab and in a mall theatre. Previous studies have shown that humans who play violent video games show clear signs of distress (negative stress), registering as higher blood pressure, as well as reports of less fullness and a tendency to prefer sweet food.

Studies suggest that watching scenes of an action movie may cause distress, a condition that can increase food intake in the absence of hunger. One study found action and adventure movies also lead television viewers to eat more calories - but only if the foods are within arm's reach. With action movies, people seem to eat to the pace of the movie. In contrast, watching an engaging comedy clip has been linked with decreasing tiredness, sadness, irritation, anxiety, and restlessness, while increasing relaxation and joy. Thus, watching a comedy clip may cause eustress (positive stress), which, owing to its high rewarding property, may reduce an individual's concomitant drive to eat. Another study found that female students ate fewer grams when watching a comedy program compared with food intake when watching a television (TV) documentary.

Our eyes lie

Another major factor in overeating is the 'supersize me' phenomena. Portion size is a key environmental driver of energy intake, and larger-than-appropriate portion sizes increase the risk of weight gain. Unfortunately, the size of food packaging and portions has steadily increased over the past 30 years and these super sized food portions play a major role in weight gain. Simply, people who sit down with bigger portion sizes of food are more likely to be overweight and obese while those who maintain a small portion size lower their weight. Whether it is from our parents telling us to eat all our food on the plate or our hunter-gatherer starvation mentality, once it is on our plate we tend to eat it and, as a result, overeat.

For instance, one study reported that 54% of American adults generally claim that they attempt to eat until they "clean their plates". Interestingly, very early studies showed this influence when participants who drank soup through a tube drank more when they had visual contact with the soup than when they did not. Literally, a person's eyes may influence how much they consume, leading them to be less influenced by physiological cues of satiation. As a result, their estimate of how much they have consumed and how full they are may have to do more with what they believe they saw themselves eat and less with how much they actually ate.

In a study of 51 men and women who were served lunch of different portion sizes, subjects consumed 30% more energy (676 kJ) when offered the largest portion than when offered the smallest portion. Larger portions led to greater energy intake regardless of serving method and subject characteristics. In one study, after a three month intervention subjects who regulated their portion size had a greater weight change from baseline to the end of the three month intervention period losing 3.7 kg compared to 0.1 kg in the control group. This shows that portion control is effective in reducing body weight in overweight and obese diabetic subjects.

It is time to have a think on why we overeat and put some steps in place. Simple strategies like keeping a food mood diary can help you identify any common factors in overeating. Even serving food on small plates can make a big difference to how much you eat each meal. It's time to downsize our meal sizes!

DISCLAIMER: Dr Peter Dingle is a researcher, educator and public health advocate. He has a PhD in the field of environmental toxicology and is not a medical doctor.


Peter Dingle

Dr Peter Dingle (PhD) has spent the past 30 years as a researcher, educator, author and advocate for a common sense approach to health and wellbeing. He has a PhD in the field of environmental toxicology and is not a medical doctor. He is Australia’s leading motivational health speaker and has 14 books in publication.