And it's a little more complicated than even just that. Another reality is that, at 12 bucks an hour, nobody is going to be giving you a steady 40 hours. You need extra shifts for buffers, and your shifts will be shorter.
Sure, working 50 hours a week across 7 days isn't technically more than 50 across 5 days. But it does certainly drain your will to live a lot more, from what I've seen.
And using numbers to support that idea doesn't work, it actually goes against you. A small (much smaller than most obese people will eat in one sitting) fast food meal costs about an hour of minimum wage! Buying stable calories in cereals where the time to buy and cook them can be amortized into many more servings can be amortized is actually cheaper and also takes less time.
In the US, obesity rates rise as income drops, but it continues to rise beyond the point at which income drops below a full time federal minimum wage income.
It's over-eating and under-exercising. I know this is hard for certain ideologies to accept because it means obesity is not inflicted upon victims against their will and beyond their control. If you really need to minimize their agency and responsibility for their choices you can call it addiction to food and addiction to sedentary lifestyle if it helps.