A couple of my close relatives have as well...and the feedback from them isn't very positive so to say.
In one instance, there was a meeting going on regarding taxation and such, and during the briefing, some technical discussion was going on regarding the dynamics of taxation and bla bla bla...and the PM in the middle of the briefing asked a person to go and get him some thing to eat, and later after the briefing his first response was to ask a person "Khanay main kia hai?".
Now that's what I've heard, make of it what you may.
So he likes to eat, he's a foodie. Can't blame him for that. You're absolutely right in that he ought to take affairs of state more seriously and try to prevent his appetite from taking over his thoughts particularly during high profile administrative meetings.
Besides, even if what you said is true, it proves nothing but the fact that he has his flaws. But then again, who's perfect? Nawaz Sharif's "transgressions" seem insignificant when compared with what our previous rulers have been involved in. Do ask yourself, Isn't it better for him to have an appetite for Nihari instead of Alcohol and dance parties? We all know what goes on in our Aewan-e-Sadar and PM House. What bothers me is that this nation would rather have an incompetent, insincere and an utterly fraudulent person's who's good at public speaking and marketing himself then someone who has all the virtues but is not so good at selling himself. I hope i have gotten my point acros.
Just for the record, i don't care how someone, be it a farmer or Prime Minister, lives his personal life. As long as he is sincere to this country and is fully dedicated to improving the lives of its people, he may drink whatever he wants and party in whichever way he likes, i wouldn't object a bit.
Let me reiterate, the reason why i don't believe NS is weak or stupid and insist he's perfectly fit to rule is because Pakistan has seen significant improvement in key benchmarks such as Economy, Law and Order, Investments, Drone Attacks and Infrastructure since he took office. He inherited a failing state, brought it back to realm of stability and has managed to set it on a positive trajectory. For doing all of this, i believe he deserves to be allowed keep his "extravagances" (like being obsessed with food).