The beliefs that people "just need to move more" is part of the misconception that "conveniently" puts the responsibility solely on the individual, ignoring the very real material reality they find themself in. To control once weight you need to control your diet, i.e calorie intake, but how do you do that if you don't have the time/energy/money/knowledge/tools to cook your own food, or even access to good ingredients to begin with? It's very hard.
We're surrounded by processed cheap slop that's literally engineered to make us crave it and knowing how little "extra" you need each day to slowly but steadily gain weight makes you realize it's a very steep uphill battle. In other words, it's perfectly understandable that someone is gaining a few kg, especially during stress and as we age in this hedonistic sedentary treat-nexus engineered to distract us from our own oppression.
We must imagine Sisyphus a little chubby.