Over the years many clinical studies have shown that obesity and depression tend to be co-morbid. That means that they tend to occur together without necessarily having a cause and effect relationship. When conditions tend to occur together, scientists naturally want to explore exactly how they are connected. Does obesity cause depression? Does depression cause obesity? Could there be a third factor that is driving both conditions? These are important questions, because once we know the answers, we can better direct our research and treatment efforts.
I happen to believe that both obesity and depression are often driven by a third factor-our modern Western diet. It is now clear that excessive fructose mainly from sugar and high fructose corn syrup is the driving force behind insulin resistance and central obesity. When you have insulin resistance it takes more insulin to drive glucose into your cells and high insulin levels tend to trap fat inside of cells where it can't be used for energy. Recent evidence suggests that excessive fructose can alter your gut bacteria flora, further contributing to metabolic syndrome and obesity.
When you have insulin resistance and consume rapidly absorbed carbohydrates, especially from grains, you end up with magnified glucose spikes. Over time these glucose spikes can cause damage to your nerve cells, because unlike most of the cells in your body, neurons don't have an insulin gate. That's why diabetics tend to lose their nerve function and develop neuropathy long before other organs in their body are damaged.
Over time these toxic glucose spikes can trigger a form of diffuse brain dysfunction where your brain no longer functions as intended. The first symptom you experience when this happens is craving for sweet and starchy food, pushing you to consume more of the very food that is frying your brain. You also can develop mild brain dysfunction symptoms like fatigue, anxiety, mood swings and poor sleep. At this stage of brain dysfunction you don't yet have a disease because the symptoms are mild and variable. I refer to this pre-disease condition as "sugar-brain".
As time goes by, sugar-brain can transition to a true disease characterized by up to 22 distinct brain dysfunction symptoms that interfere with your ability to function in multiple settings. I now call this disease Carbohydrate Associated Reversible Brain syndrome or CARB syndrome. Because the brain plays a key role in auto-regulating fat stores, people with sugar-brain and CARB syndrome will start to store extra fat even as they diet and lose weight and lean body mass.
The symptoms of sugar-brain and CARB syndrome develop because people with these conditions have low levels of monoamine neurotransmitters like dopamine, norepinphrine and serotonin in their brain. When these neurotransmitters are low, regardless of the reason why they are low, you end up with predictable symptoms. Some of these symptoms would easily qualify you for a diagnosis of depression.
It's important to remember what true hereditary depression looked like 100 years ago. At that time all patients with major depression felt depressed, lost their appetite and lost weight. There was no such thing as a "weight gain" type of depression. This situation has radically changed over the past 30-40 years. Today most patients diagnosed with depression feel depressed, have an increased appetite and carbohydrate cravings and weight gain. In my opinion this form of depression is CARB syndrome, not true major depression. Unfortunately the medical and scientific communities lump both types of depression into one category, when in fact they are dealing with two distinct diseases. Suffice it to say that the great majority of people diagnosed with depression today, in reality have a form of food-induced brain dysfunction called CARB syndrome.
A recent study published in the journal Molecular Psychiatry by Dr. Mark Hamer titled
"Risk of future depression in people who are obese but metabolically healthy: the English longitudinal study of ageing" supports the view that obesity and depression are connect through metabolic parameters, not obesity per se.
Remember that there are really two types of obesity. The most common type is associated with insulin resistance, metabolic syndrome and type II diabetes. This is the form of obesity that we tend to see with CARB syndrome. The second type of obesity is where a person has excessive body fat without any of these adverse metabolic markers. This type of obesity is seen when a person or lab animal is over-fed healthy food. If you give enough healthy food to any animal, they will eventually develop this type of obesity.
The type of obesity associated with sugar, HFCS and grain-based carbohydrates is not dependent on calories or over-feeding. Although people with this form of obesity always have excessive body fat, especially in the abdominal region, they may not be over-weight and they can sometimes even be thin. It's important to remember that obesity is defined as excessive body fat, so don't be fooled by someone's size or weight.
In this particular study they looked at the correlation between both types of obesity and depression. They wanted to know about the connection between depression and people with "metabolic obesity" and those who were obese but metabolically healthy. As it turns out people with metabolic issues were at an increased risk of later developing depression, whereas those who were obese without metabolic issues were not at an increased risk of developing depression. This is exactly what we would predict from the CARB syndrome disease model.
How does this information apply to you? I assume that most of you would rather not be obese or depressed. If insulin resistance and metabolic syndrome are the gateway to most cases of obesity and many cases of depression, the best strategy would be to prevent metabolic problems or to treat them aggressively if you already have them. The best way to do so is to limit your intake of the dietary triggers of insulin resistance and metabolic syndrome-sugar, HFCS and high glycemic carbohydrates, especially from grains.
Of course this describes most processed foods that form the core of the modern American diet. Learn to eat real food including meat, fowl, fish, seafood, vegetables and fruit. I'm not a big fan of milk because of its sugar content but a reasonable amount of cheese is acceptable. I would also limit your intake of legumes because of their anti-nutrient content. Some would recognize this as a Paleo-style diet. I simply call it a healthy diet.
If you learn to eat this way you will go a long way towards preventing the metabolic problems that seem to lead to many cases of obesity and depression. There are also many other common conditions that fall under the CARB syndrome umbrella. As with depression, we now believe that the diseases listed below can be triggered by eating these toxic dietary elements.
繚 Anxiety disorders
繚 Eating disorders
繚 Irritable bowel syndrome
繚 Restless leg syndrome
繚 Bipolar II
I think that it's really exciting that we have now made a connection between food and these common disorders. Think about it. What would you rather do-take handfuls of pills for the rest of your life living in a daze, or simply change your diet? This important study clearly shows the relationship between consuming certain foods and depression. In the years ahead I hope that we will see more studies looking at the impact of diet on common chronic diseases. Gary Taubes, author of the excellent books "Good Calories, Bad Calories" and "Why We Get Fat" has started a non-profit organization called NuSi that is dedicated to funding such research. I plan on supporting Gary in his efforts and I encourage you to do so as well. I don't think that we can count on the agricultural or food industries to fund this type of research so we're on our own. If we are going to stay healthy, we need to stick together.
If you want to learn more about the role that excessive fructose plays in driving metabolic problems, I recommend that you read Richard Johnson's book "The Sugar Fix" or his excellent new book "The Fat Switch". It's never too late to learn and it's never too late to change. For the sake of your health and mental wellbeing, I suggest that you start today.