> What are the other possible factors [than food]?

Could be stress levels, perhaps due to imprisonment of family members or economic inequality, both of which have skyrocketed in the US in recent decades. Other aspects of economic inequality, such as a shift toward emergency medical treatment, are also possible causes. It's observable that the social classes most affected by obesity in the US (and, now, worldwide) are the poorest; this might be due to food, but it might not be.

Could be infectious diseases, which are always changing, or more generally, microbiome changes. Diet changes (e.g. increase in sugar, or increase in usage of emulsifiers such as methylcellulose: http://www.nature.com/news/food-preservatives-linked-to-obes...) are one possible cause of microbiome changes, but far from the only one. For example, obesity-associated intestinal microbiomes have been shown to be contagious under some conditions: http://www.nature.com/nature/journal/v444/n7122/full/nature0...

Another possible cause, though: antibiotics are well known to cause microbiome changes (although maybe this is still "has something to do with food", since most of the antibiotics you consume during your lifetime are in meat.) And antibiotics are also known to induce weight gain — that's why they get put in the meat in the first place, to induce the meat animals to gain weight faster, reducing the time to slaughter. Maybe they make you gain weight too, and they might do that by means other than changing your gut microbiome. Antibiotic use, both in humans and in livestock, has undergone substantial changes over the past decades, and their possible effects on obesity are not well understood.

Another possible cause: dramatically increased air travel and the ensuing jet lag; circadian rhythm disruption has been shown to induce metabolic dysfunction in a wide variety of animal models. http://www.pnas.org/lens/pnas/111/47/16647

For the same reason: artificial lighting. Artificial lighting color temperature as we switch from incandescent to fluorescent, LED, and computer and TV screens.

Sedentary lifestyles are a possible cause — rates of "exercise" are only going up if you don't count manual labor as "exercise", and rates of manual labor are going way down.

Worldwide testosterone levels are falling for unknown reasons; testosterone is very well known to reduce body fat. http://www.globalresearch.ca./health-and-the-environment-tes...

One possible hypothesis advanced for the dramatic testosterone level drop is exposure to environmental contaminants such as pesticides; the pesticides we use, the amount we use, and the places we use them have changed dramatically over the last few decades. Whether or not this affects our testosterone levels, it could easily affect our bodies in other ways, possibly promoting obesity.

(Other factors that are known to lower testosterone levels include stress and lack of exercise.)

Other environmental contaminants with dramatically changing exposure levels over time and that might reasonably be endocrine disruptors include PCBs, phthalates (as the above article mentions), bisphenol-A, lead, and the halogenated flame retardants used in polyurethane foam, which have been circumstantially implicated in the modern epidemic of feline hyperthyroidism. The lower levels of lead and PCBs in the environment are probably good for us, but sometimes there are surprising interactions.

> the probability that out obesity epidemic isn't 100% due to diet is zero.

You, you are an arrogant, pompous idiot, too ignorant even to begin to imagine the extent of your own ignorance.