You pay is not a reward, a bonus is. You pay is part of a fair exchange.
Pay for work is not a reward, a bonus is. Your pay is part of a fair exchange. Rewards are over and above a fair exchange.
Apart from that, you should know that when i said i don't believe in rewards, i mean rewards of food.
A reward
is a fair exhange, not more than. Rewards are what a person deserve, what they have earned.
A reward is something that a person is given when they do something that earns the reward in question. For instance, when I write articles for my freelance writing job and they get accepted by the publisher, my reward for that is seeing money deposited into my bank account. Or, when I follow a proper diet and exercise routine for 3 months, my reward is losing weight and feeling better about myself. I get what I deserve. I get rewarded for my efforts.
Without rewards, people would never feel that their efforts are appreciated or worth while. And, if that were to happen, what motivation to people have to do any work or put in any effort? Why work for 10 hours a day if I'm not going to get rewarded with a paycheck? Why work for nothing? Who would do that? Why work really hard, but have nothing to be rewarded with - to have nothing to look forward to?
And, I know you were referencing food when you said you don't believe in rewards, but the same logic of being rewarded for laborous work applies to putting in effort to lose weight (eating healthy, exercising, etc).
Without being rewarded, why would someone put in the effort to lose weight?
If someone eats salads, fruits, vegetables and other healthy food items for the entire week, knowing that they have a big ass piece of greasy pizza waiting for them on the weekend, is something they can look forward to - it is something they can use for motivation.
"Man, I'm sick of eating salad. But, it's Thursday. Only two more days of this and I can enjoy a piece of pizza. So, you know what? I'm going to tough it out for these next two days, because I know I can take a break on Saturday when I enjoy my delicious pizza. I CAN DO THIS!!!"
That motivation of knowing that their work of eating healthy all week long will be rewarded with a big slice of pizza on Saturday is something that can carry a person through their times of struggle. Without that reward, they wouldn't have motivation - they wouldn't have something to look forward to. Without that reward, their struggles might get worse and worse and worse, leading them to ultimately fail.
Not everybody has the will power to walk through life without being rewarded.