Bushwalk Australia

I was in an event on the weekend covering 100km. As a team of four we each carried appx 5kg.
We bettered our time, as we have done four times before.
I showed no obvious signs of a cold beforehand but immediately after it's all on. Chest, voice, throat.
This time I was the weakest of the four, only noticeable on the uphill. All the time struggling at half their pace.
It was pretty much the opposite on previous occasions.
I ate very little enroute but plenty beforehand. Everything I recall trying on the walk tasted shocking. I had to spit it out.
Sandwiches, even banana to some degree. Chewing gum was bad.
My question to others is 'have you ever experienced the food tasting bad as a result of fatigue?
It may well have been the cold developing in me.

It probably was due to the cold developing. Loss of appetite commonly accompanies a cold.

But if your food isn't tasting good under normal conditions, you perhaps don't have enough fat in your food. Bananas, etc, are great for a quick burst of energy, but after a while your body can use some fats too. How does a piece of cheese or salami taste?

i have to eat pretty plain food when i'm on the go and in small amounts frequently... or it can make me sick
your metabolism changes during exercise... especially if you're sick or not fully fit...
ultrarunners can have a lot of problems holding food and liquid down the further they go
exercising produces acidic biochemicals your body has to neutralise. over time you can fail to neutralise them adequately and your body fluid goes acidic, this changes things like your tolerance for food... any food that is acidic or rich food is likely to be rejected, more extreme you'll just reject a whole raft of food or all food.
plus if you're bodys already trying to process food its digesting that can upset things further.
you're ability to digest fat and protein plummets when you're exercising , the more intensely you exercise the less it will be able to digest them..
sugary food requires more water and is prone to upsetting your gut and fermenting especially when combined with slow digesting food. carbs are one of the better choices..
slow down and let your metabolism sort out the toxic byproducts in your system and you should get some restoration of your appetite.

Change in taste and smell is common with viral illnesses of the respiratory tract.