What are your thoughts on obesity and addiction being related?
I think there's clearly a relation. People with an addictive personality have a "broader" dopamine reward circuit in their brains. This personality will manifest itself by obsession with an activity that releases dopamine—gambling, drugs, and (yes) sugar.
Using Positron Emission Tomography (PET) researchers have shown that reward dependence is linked to opiate receptor binding (the endorphine system) in the bilateral ventral striatum: a core substrate of the reward circuit which is strongly implicated in addictive behavior development. These findings demonstrate that people with high reward dependence (who feel a greater need for social rewards and verbal approval) have more opiate receptors found in the ventral striatum, whereas people with low reward dependence have a lower concentration of receptors.[20] It is then suggested that increased ventral striatal opiate receptors could provide the biological link between personality traits and substance abuse risk.
The man in this documentary exemplifies an extreme version of this. For him, fatty and sugary foods were his replacement for a meth addiction.
Would you agree that just telling someone to eat less is like telling an alcoholic to just stop drinking?
I think telling someone to "eat less" is sufficient if they really want to change. Most people aren't really ready to change.
I would say "eat differently", much like I would tell an alcoholic to "socialize differently". Read Charles Duhigg's "The Power of Habit"; he explicitly talks about Alcoholics Anonymous and how you replace destructive reward behaviors rather than deny them, which requires more willpower than most people have.
But how does society help people who actually want to break the cycle of addiction?
Solutions that work for individuals and solutions that work for societies are not the same. You can improve a man; you can't improve men. Any attempt to decrease to obesity will mean changing the environment people live in—walkable cities, education, cheap/healthy restaurants or more time-off for home cooking, regulation of advertising for particularly addictive foodstuffs (as with cigarettes)...
Unfortunately, I think addiction to something is a natural inevitability. The flaw lies in brain chemistry. If we change people's environment to discourage overeating, many will probably find some other vice. I would love it if governments could somehow help society as a whole to become self-actualized and transcend cheap dopamine hits—but I suspect that's as impossible as Marx's Workers' Paradise.