There is a school of thought which accepts both of those as factors.
The diet one is decidedly dodgy, though. Every worker expends energy.
It's part of being a worker and doing work, for which normal pay/salary
is the consideration. If the cost of food for a cyclist doing official
travel was valid (I say it isn't), manual workers who do very heavy work
would have a much better claim on "expenses" just for doing their normal
job.
The wear and tear argument is much more of a sound basis for the payment
of expenses, subject to a fixed limit (just as applies with motor
vehicles, even if the employee uses a vintage Bentley).