Yeah, the proximate cause is eating too much but the ultimate cause has to be systemic if we're getting more and more obese all the time.
I ate all kinds of protiens and fats - cheese, meats, fish, veggies just to quell the hunger. I lost about 58 pounds in a year. Most of what I lost was fat. Two years later, I'm still doing a very low carb, but keep it under 50g per day. My weight has stayed ±3 pounds. I'm pretty convinced it's the super-high carb load everyone is eating three times per day.
The ultimate cause is consuming too much, the proximate causes are various elements of modern culture (i.e. Bigger serving sizes, more readily available snacks, alcohol consumption, etc).
I think sugars and processed food increase hunger rather than reducing it.
(1) Share of physical labor jobs vs office jobs
(2) Increased hormone and pesticide use in agriculture (dropping worldwide sperm counts is an underreported story, might or might not be related)
(2A) Less nutritional content in food - has gone down 60% since 1940s according to some studies; likely from over-farming. Need to eat more to get the same nutrients.
(3) Food deserts (related to (1)) - where healthy food options are rare
(4) Less general socialization (internet makes it less necessary to go outside, etc)