Obesity is not simply a problem of overeating. The causes of obesity are very complicated. A small portion of food which may not sufficient for the needs of a normal person, may become too much for person prone to obesity.

The most prominent cause of obesity is infectious diseases and inflammation, and the term infectobesity was coined by Dr. Nikhil V. Dhurandhar in 2001:

Article Infectobesity: Obesity of Infectious Origin1

The up-regulated autophagy (xenophagy) triggered by infectious diseases turns the eliminated pathogens and dysfunctional cell components into nutrition and energy, which turns out to be over-nutrition if the person is still eating normally. So obesity is a side effect of our body’s protective reaction to illness.

Obese people will normally eat much less than normal people. And even if they eat less, it is still very hard for them to drop the pounds. Stigmatizing obesity and Blaming the obese people of being greedy and eating too much is actually not fair to them.

Obesity is normally measured by BMI. Yet, the big contributor to BMI is the subcutaneous fat, which is protective and normally harmless. But one relatively small component of the obesity, the excessive visceral fat and ectopic fat that surround the organs or enter the organ tissues, are very dangerous, which contributes to morbid obesity, and is associated with numerous diseases.

Ligen Yu I have heard (I believe on National Public Radio, NPR) this before about obesity being caused by a viral infection. Now I have followed a documentary that has shown that different gut flora can have an impact on obesity. There was a case when a woman got a fecal transplant she started to gain weight. She got the fecal transplant from her daughter and her daughter was overweight. I assume some species of bacteria metabolize at a faster rate than others or cause inflammation. I have also read that women who breast feed their children are at lower risk of obesity. I have argued because of gut bacteria. I also read the use of antibiotic can cause obesity. I do know that antibiotics are used to fatten up livestock by reducing bacterial load in the gut. With that there emotional eating, or eating when one is upset or in a bad mood (also gut bacteria can influence mood, lactobacillus can produce serotonin which can move up the vagus nerve to the brain, I have experience with this by drinking buttermilk on a daily basis which actually improved my own mood).

I am not saying people are greedy for food, there is a psychological cause due to a food scarcity or a food security issue. A real anxiety over a lack of food which causes a person to overeat when food is around, even when there is no issue with scarcity or security. There are cases for example of neglected children when they are brought into foster care or are adopted, they have food security issues and will try to eat all of the food they see because of a fear they will have no food available in the future. Basically an anxiety over a lack of food so the individuals overeat because they do not know when their next meal is coming. There was a case of a woman who survived WW II as a teenager. She always kept pieces of bread in her pockets in order to survive, and when she had her son she made him keep bread in his pockets, even when he was an adult she would put pieces of bread in plastic bags and tell him to keep them in his pockets. There are people who survived the Great Depression who will not waste even a mouthful of food.

Dear Jonathan Wayne Riddle , thank you for your reply. So sorry that I misunderstood your title post. Agree that emotional eating do contributes to overweight and obesity. More often that not, we behave on our instincts, not after careful reasoning. And such behavior may eventually not good for our health (like emotional eating may lead to morbid obesity and metabolic syndromes).

So a calm, peaceful and worry-free mind is always preferable for our health.

The world is going obesogenic due to binging . Food addiction is even more within the wealthy. Abnormal brain chemistry is the key reason. when the levels of brain biochemicals ( dopamine, acetyl choline , GABA and Serotonin) drop, we eat junk foods, calorific level rises , metabolism drops in rate, obesity sets in. Get brain biochemicals right , binging stops and obesity is controlled

There are a positive correlation betetwen insulin and obesity. So that any food like carbohydrates stimulate insulin can cause obesity.

Jonathan Wayne Riddle there is some evidence pointing to higher prevalence of obesity in food insecure individuals. Food insecurity is likely correlated to several well-established risk factors for obesity, including diet. It is also strongly correlated with income and education levels, and likely has an impact on psychological well-being and other lifestyle-related factors (eg, sleep, physical activity). I believe that the idea that you are mentioning is probably an important contributor to the increased risk of obesity in food insecure individuals, but it is also only a part of a much bigger and complex picture.

Interesting read on the topic:

Dhurandhar EJ, (2016). The food-insecurity obesity paradox: A resource scarcity hypothesis, Physiology & Behavior, 162:88-92. doi:10.1016/j.physbeh.2016.04.025

The two are unrelated.