Dog has decided he no longer likes his usual food.

[Balula]

My pup has always been fed on Butternut boxes, he's always wolfed it down with gusto, no issues.

The last couple of weeks he's slowly started refusing to eat certain flavours and now we're down to just one that he will pick at.

He is however begging for our good and stealing food if he can leap and get it so he's obviously hungry.,

Do I continue with the Butternut and persevere or do we change him to something else? It's a lot of money to lose if he's going to turn his nose up at it.

He's otherwise healthy.

Stolen food is always the most exciting
Mine went off food when she was teething lasted about a week of being really picky not even interested in treats.

Wants a nice bit of steamed chicken and broccoli. But don't give her garlic bread or she'll blast her muck all over your rug.
Another thing to try is one of the posher brands like Lotus or Chien Prix.
Has she been smoking fags? This will put her off her grub.

Maybe we are dog spoilers, but we have a little "poo" type who is too smart for his own good. He will eat something with gusto for weeks, then walk up, sniff, and walk away.

He always has a 1/2 small bowl of small dog kibble (not grain free but good quality). Then about a tbsp and a 1/2 of a very low fat moist food as he has had pancreatitis.

We vary the wet food fairly often. Right now he has lamb and rice. Sometimes Chappie which is whitefish based. Sometimes salmon based with sweet potato. He does like chicken pare, beef and veg etc.

It seems to work but boy oh boy he can be fussy.

I think they get bored of same old every day. Just like us.
Store the current stuff for another time.

Mine went through a phase of this - the only answer was tough love.

Meals at set times only. Put food down, leave for twenty minutes and then remove bowl. No more food - treats or otherwise - until the next mealtime. Repeat as needed.

They soon learn to eat what they're given!

I wouldn't persist. I don't really trust the ingredients in commercial dog food-saw dust, horse parts, old carpets, and so on. I find it easier just to cook the dog her own food.

She just have biscuits too but often refuses then from the bowl. When this happens, I put them in a squirrel toy / Kong toy, and she'll happily eat them from that.

Hmmm be careful, my mini schnauzer is the same and we have given in too often. She’s now overweight! Fussy eaters can put weight on by snacking and grazing instead of eating their food.

I would gradually switch over to something he will eat.
No point spending money on food that gets chucked.

One of mine has to have his food on rotation, and even then will sometimes go off something totally. Thats fine, I'd get bored too, so we just find other things for him to add into the options

Have you tried warming it up a bit? My dog used to have butternut box, had to change when their freezers broke and they couldn’t fulfil my order. Now on different dog which is a similar kind of food, think they do a trial box.

What's been happening when he first started to show a lack of interest? If he's been getting something tastier from you then I suspect switching dog foods isn't going to solve the issue as he needs to learn that he should eat his own food whilst it's available.

As you say, he's clearly hungry and he's not going to starve himself if he knows that is the only food available, try putting it down for ten/fifteen minutes and if he hasn't eaten pick it back up. Don't give him anything else instead. After a few meals he'll realise he'd better eat his own food whilst it's available.
But to be honest, it completely depends on you. If that sounds too mean then you could always try swapping foods but I do think if you start going down the route of trying to increase palatability by microwaving or adding in extra tasty things you will have to keep doing that, probably much easier for you to teach him to eat his own food again, which he used to eat very happily.