The Antidepressant Diet

The connection between carbohydrates, serotonin, and antidepressant weight gain

Depression after Gastric Bypass Surgery

Could it be the lack of carbohydrate?

For those whose weight has climbed steadily after years of failing on traditional diets, gastric surgery to reduce the size of the stomach seems almost inevitable. If the stomach pouch is made so small that it holds about the same amount of food that would feed a gnat, weight loss is inevitable. So little food can be eaten at a time that patients are told not to drink water at mealtime because doing so leaves no room for food. Pounds seem to melt off, leaving the post-operative patients optimistic about improved health, energy, and a lifestyle no longer limited by excessive weight.

But for some, as the pounds disappear, the problems begin. Nutritional deficiencies due to changes in absorption of food into the body are well characterized but handled by monitoring of food intake and vitamin-mineral supplements. Eating too much causes severe nausea and pain, another unpleasant but avoidable side effect if the temptation to take one too many bites is overcome.

However, some problems don’t disappear as quickly as the weight, and for some, may persist for years. Anxiety, depression and insomnia may be so severe and resistant to medication that some patients consider having the operation reversed. Anxiety about the operation is understandable. Who among us awaiting any operation has not awakened at 3AM with a pounding heart and in a cold sweat thinking about the procedure about to be done? And anxiety after the stomach reduction is also understandable. There is no rehearsal time to prepare for an entirely new way of eating and a newly emerging body. Clinical depression and insomnia are not so easily explained.

One could surmise that depression might follow the realization that certain foods are never again going to be eaten. Presumably waking up after surgery and knowing you would never eat chocolate again might put you into a permanent funk. But the depressions reported both in the scientific literature, and in the hundreds of personal anecdotes on gastric surgery blog sites, suggests otherwise. Some have associated depression with the very low-calorie diet followed for several months following the surgery. Studies carried out during and post-World War II on volunteers given a semi-starvation diet similar to those in prisoner of war camps showed significant depression that disappeared when the subjects were given enough food. For some, however, a clinical depression lasts well beyond the first months of very restricted feeding and is resistant to antidepressant therapy.

Could the cause be the lack of a specific nutrient in the diet, i.e. carbohydrates? The absence of carbohydrate in the diet invariably alters serotonin levels and that neurotransmitter activity. It is the insulin release after carbohydrates are eaten that indirectly allows more serotonin in the brain to be made. Insulin changes the levels of amino acids in the blood and this enables one amino acid, tryptophan, to enter the brain. Serotonin is made from tryptophan, and thus is dependent on its brain availability.

Dietary regimens before and after bariatric surgery often create the perfect storm for serotonin depletion. High-protein/very low-carbohydrate diets are imposed on pre-surgical patients so they will lose some weight before surgery. Post-operatively, patients eat only protein and supplements to prevent muscle, vitamin and mineral loss. Even though tryptophan is one of the amino acids making up protein, studies done over several decades at MIT showed that when protein is eaten, little or no tryptophan enters the brain.

Low and/or inactive serotonin is associated with depressed mood and anxious mood, anger, irritability and fatigue. Women normally have less serotonin in their brains and are more likely to be depressed than men. Might their depression after bariatric surgery be related to their serotonin depleting diet?

How to increase serotonin production during the protein feeding phase is a difficult problem. The stomach is so small, there is not room for both carbohydrate and protein and the latter must be eaten. Would giving tryptophan as a supplement help? Should studies be done to see if increasing the synthesis of serotonin prevents or decreases depression?

Insomnia is also an unexpected side effect of the surgery. Other than patient reports, not much is known about the cause or how to handle it. “I was awake until 2AM, fell asleep, and then woke up at 4 AM. The only way I can sleep is by taking prescription sleep medication,” is not an uncommon description of persistent wakefulness of many post-surgical patients. According to some of their reports, the insomnia lasts for months and even years. Some people reported taking melatonin but in such large doses (the correct dose is 0.3 mg) that it shut off their body’s own production of this hormone and stopped working. Others would attempt to limit the use of prescription drugs for fear of addiction, but eventually give in after several sleepless nights.

Would eating more carbohydrates help? Might more serotonin help calm and soothe the mind so it stops racing around like a gerbil on a running wheel and allow sleep to come?

No one disputes the life-saving consequence of bariatric surgery as it removes or decreases the many health problems of excessive weight. But unless depressed, insomniac individuals find some way to feel and sleep better, they are a risk for regaining weight and losing their health. Call it an unexpected blindside of a surgery meant to make life easier to begin with.

Judith Wurtman, Ph.D., is the co-author of The Serotonin Power Diet and the founder of a Harvard University hospital weight-loss facility.

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