See https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8747021/ for a review article.
Summary: there are many risks, from menu fatigue, energy consumption vs expenditure (e.g. exercising), adverse effects of space travel from microgravity, long-term radiation exposure, metabolic stress, and so on.
That's not what your link says. It actually says:
"It is estimated that a 3-year Mars mission with a crew of six would have a total energy expenditure of 12 megajoules per person per day, regardless of water requirements, and would carry 22 tons of water-containing food on the spacecraft"
Thinking about hiking/camping, with dehydrated food 3 calories per gram is fairly standard.
22 tons at 3 calories per gram is about 7.3 million calories.
That's 3000 days at 2500cal/d.
But when you're hiking you can just source water along the way. You can't do that on a Mars journey. Can you do it on Mars?
edit: in response to the recycling comment - of course! doh! then it should be easier, no?