Why Dieting Can Cause Depressive Symptoms

Medical Reviewer

Any disruption to a normal balanced diet has the potential to cause depressive symptoms, or make existing symptoms worse. Disruption to diet is fairly commonplace in people who already experience low moods or depression; they may go off food, or eat more. Everyone knows we have to eat in order to survive, but it is the kind of food we eat that influences our health and wellbeing.

It's so easy to pile on the pounds. Sedentary lifestyles coupled with those convenience foods and tempting treats quickly show on the waist and hips. The speed at which we can put on weight isn't matched by the rate we can remove it. The temptation then is to embark on a restrictive diet. Not only can this feel physically uncomfortable it can also have an effect on mood. The slump in mood that frequently accompanies such diets can make people feel so miserable and constrained they lose motivation and turn back to food. When their mood lifts, they associate this with not being on the diet, and so begins a powerful incentive to continue as before. However, the internal processes that cause the mood to slump in the first place are hidden, so it helps to know about these before making any changes to diet.

Food contains many of the requirements our brains need to function properly. One important component, an amino acid called tryptophan, is needed to produce a neurotransmitter called serotonin (see, a brief guide to serotonin). Serotonin has an important effect on mood, so any depletion in tryptophan is bound to have a knock-on effect. A diet that is poor in tryptophan may have no immediate effect on people without depression, but experiments have shown that recovered depressives can feel symptoms of depression within hours of tryptophan depletion. Returning them to a normal diet shows a lifting of symptoms. Understanding the link between depression and diet also reveals the importance of standing back from a diet of highly processed foods.

Crash diets - those that restrict calorie intake to around 1000 calories for women or 1200 for men - cause a significant decrease in tryptophan. Women, it appears, are more sensitive to the effects. Many people with anorexia or bulimia suffer from depression and the assumption is that reduced tryptophan intake is also reducing the normal production of serotonin.

When a restrictive diet collapses, the usual cravings for carbs and sweet stuff can be satisfied. It's no coincidence that we crave such goodies as our bodies are telling us they need the energy. Not only that, carbohydrates help in the absorption of tryptophan and so the puzzle begins to be solved as to why such foodstuffs are craved. The issue for most people is that energy consumed, is supposed to be burned up. We put on the pounds when intake is higher than output, but the nature of what we eat is very influential in how we feel. Many convenience foods are high in fats and sugar and leave the person feeling they can eat more.

Effective weight loss is really a process than can take many months to be fully effective. Smaller steps, coupled with exercise and a balanced diet, is far better for the body and the brain.