If you take antidepressants, they may be causing a serious side effect that you are not aware of. Fortunately, the solution can be found in relying upon a healthy diet to balance your inner ecosystem and greatly improve your digestive health.

Did you know that antidepressants might cause weight gain?

A recently published article by Dr. Judith Wurtman underscored this fact, and readers’ responses were overwhelming: weight gain is not typically addressed as a side effect of antidepressant medication, and most patients feel frustrated and confused.1

According to pharmaceutical sales in 2009, six of the top fifteen medications were either antidepressants or antipsychotics.2

For perspective, the top five selling pharmaceuticals were:

  1. Lipitor: Reduces LDL (low-density lipoproteins) in blood and triglycerides
  2. Nexium: Reduces the amount of acid produced in the stomach
  3. Plavix: Inhibits platelets in blood from coagulating, commonly used after heart attack or stroke
  4. Advair Diskus: Inhibits inflammation and is a bronchodilator
  5. Seroquel: Antipsychotic that “changes the actions of chemicals in the brain”

These top-selling medications all have something in common. Besides the fact that they all inhibit critical biochemical pathways and are over-prescribed, they all imply a diet that does more harm than good. High levels of “bad” cholesterol, heartburn, heart attack, inflammation, and even psychosis or depression are all conditions that at the very least are made worse by eating the Standard American Diet (SAD).

Dr. Wurtman, co-author of a book offering a weight loss program for those who have gained weight while taking antidepressants, tells her readers that it is difficult for people to understand the connection between brain chemistry and weight. Her article, which in itself received hundreds of comments responding to the connection she draws, makes an important point: medications that affect brain chemistry might also affect weight, which I’ve taught for years through the importance of the inner ecosystem.

Did you know that 80%-95% of the body’s total serotonin is produced and found in the gut?

That’s right. The enteric nervous system (ENS) controls the gastrointestinal tract and has over 100 million neurons. The rest of the neurons in the human body are located mostly in the central nervous system (CNS), which is the brain and spinal cord. Dr. Michael Gershon is known for bringing these details to light in his book, The Second Brain. The gut, essentially, has a mind of its own and is in constant dialogue with the central nervous system. This cross-talk between the gut and the brain is known as the gut-brain axis. I refer to all of the communication in this area as the abdominal brain. That is why it is imperative to establish a healthy inner ecosystem with beneficial microflora.

Antidepressants and antipsychotic medications affect neurotransmission and chemicals in the brain. With some medications this effect is not understood at all. For example, the mechanism behind Zyprexa, which ranks number fifteen in sales for 2009, is openly not understood by doctors. Most other antidepressants and antipsychotics directly block serotonin receptors in the brain. If up to 95% of the body’s serotonin is produced and located in the gut, do you think that this kind of medication would also affect gastrointestinal health? As it turns out, small doses of select serotonin reuptake inhibitors (SSRIs), like Lexapro, are used therapeutically in the treatment of irritable bowel syndrome (IBS).3

The gastrointestinal immune system, the intestinal mucosal barrier, and the microflora of the gut are all in constant dialogue.

Not only does the gut house over 100 million neurons, it also possesses the largest mass of lymphoid tissue in the human body. This mass, known as gut-associated lymphoid tissue (GALT), is the digestive tract’s immune system and sits just below the mucosal barrier of the intestines. The mucosal barrier keeps the gut microflora and other contents of the intestine in place. Inflammation makes the intestinal tract permeable, and beneficial microflora actually help to repair the lining of the gut.

The friendly bacteria found in the gut are involved in intestinal development, immune modulation, gastrointestinal motility, and drug metabolism. They break down toxins and carcinogens, create micronutrients, and prevent pathogenic bacteria from taking up residence. They also alleviate depression.

What happens in the gut is often reflected in the brain.

An inflamed, leaky gut can lead to what is known as a “leaky” brain. When the gut becomes permeable and inflamed, this activates pro-inflammatory cytokines (regulatory proteins released by the immune system). This can lead to a kind of mental depression and lethargy that is induced by cytokines.

Again, the gut-brain axis plays a pivotal role. This is because these pro-inflammatory cytokines from the gut can actually cross the blood-brain barrier and stimulate certain enzymes, which leads to a peripheral depletion of tryptophan.4 Tryptophan is an amino acid precursor to serotonin.

This is one possible reason why patients taking SSRIs and other medications to treat depression do not go into complete remission: rather than treating systemic inflammation, the treatment principle involves disrupting serotonin metabolism.

What’s interesting is that physicians made the connection long ago.

In 1932, the New England Journal of Medicine published a paper with the title, “Colon Irrigation in the Treatment of Mental Disease.”5 Later, the American Medical Association (AMA) dismissed this as quackery. However, in recent decades scientists are seeing the physical link between the gut and mental-emotional states. This is why currently a great deal of attention is being paid to not only the gut-brain axis, but also the tenants of the gut, the friendly microflora.

Those who struggle with obesity actually have different microflora in their gastrointestinal tract than those who are comparatively lean.

Recent studies have found that certain microbes extract more energy from foods than other microbes. This means that if these microbes are present in your gut, you could eat less than the average person and still carry excess weight.

Dietary factors and chemicals you ingest can lead to long-term changes that determine which microbes inhabit your gastrointestinal tract. According to research, regulating the microbes in the gut and balancing the inner ecosystem with probiotics is one very important component of maintaining a healthy weight.6


  • When treating depression and managing possible changes in weight, it is important to understand that mental health and digestive health are deeply connected. While there may be other factors involved, such as your adrenals or thyroid functioning at suboptimal levels, making sure your gut is in a state of health is a good place to begin. Always check with your physician before making changes to your regimen.
  • Take a probiotic supplement and eat foods rich in beneficial microflora. If you taking a medication for depression and would like to explore alternatives or simply help your body create a greater sense of homeostasis, including probiotics into your daily routine is one of the most important steps that you can take.
  • Including easily digestible and organic foods that are high in tryptophan will support the natural production of serotonin. Most animal products are high in tryptophan. However, unless they are fermented like dairy kefir, you may find them hard to digest. Spirulina is a vegan protein source that has a very high percentage of tryptophan. Body Ecology’s Super Spirulina Plus is a good source of spirulina that has been fermented. This means it is predigested and easily used by your body.


  1. Wurtman, Judith. The Cause of Weight Gain People Don’t Talk About 3 Dec. 2010: Huffington Post.
  2. “Pharmaceutical Sales 2009.” drugs.com. Drug Information Online.
  3. Brownstein, David. Drugs that Don’t Work and Natural Therapies That Do!. West Bloomfield: Medical Alternative Press, 2009.
  4. Wichers, Marieke and Michael Maes. “The Psychoneuroimmuno-Pathophysiology of Cytokine-Induced Depression in Humans.” The International Journal of Neuropsychopharmacology. (2002) 5: 4: 375- 388.
  5. Marshall, Harold K. and Charles E. Thompson. “Colon Irrigation in the Treatment of Mental Disease.” New England Journal of Medicine (1932) 207: 454 -475. .
  6. DiBaise, John K., et al. “Gut Microbiota and Its Possible Relationship with Obesity.” Mayo Clinic Proceedings (2008) 83: 4: 460 – 469. .

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