Prevent hamster obesity with the right food mix

Hamster welfare requirements are significantly more demanding than the typical starter cage suggests — they need very deep bedding (at least 30cm) for burrowing, a large wheel (28cm+ for Syrians), and a cage far bigger than most sold in pet shops. That said, diet is just as easy to get wrong: overfeeding seed mixes is one of the most common causes of obesity in house hamsters, and it happens gradually. Before I help you nail the right quantity and food, can you tell me what species you have, how old they are, and what you're currently feeding them?

That's a really common habit and easy to fix once you know what you're working with. Syrians should get roughly one level tablespoon of dry food mix per day — around 10–15g. The bowl-topping method causes problems because hamsters hoard food in their burrow and then you top up again, so they're actually getting far more than you think. What are you currently feeding her? A lot of cheap seed mixes are also very high in sunflower seeds and fatty ingredients, which speeds up weight gain considerably.

Yes — supermarket seed mixes tend to be high in sunflower seeds and sugary bits that hamsters will selectively eat, leaving the healthier parts behind. I'd switch to Harry Hamster Complete Hamster Food. It's a well-balanced mix that includes a good variety of seeds, grains, and pellets with a much better fat and protein profile than most supermarket options. Measure out one tablespoon daily, scatter it in her enclosure or place it in one spot (not a bowl she can hoard directly from), and check her cheek pouches before topping up — she's probably squirrelling a lot away. Combined with a big enough wheel so she's actually burning calories, you should see her slim down steadily over 6–8 weeks.

Small amounts of fresh food are fine and actually good for enrichment — a fingernail-sized piece of cucumber, broccoli, or plain cooked chicken a few times a week is ideal. Avoid fruit for now while she's losing weight; the sugar content is too high. And skip commercial hamster treats entirely — yoghurt drops and honey sticks are essentially junk food. Once she's back to a healthy weight you can reintroduce the occasional tiny piece of fruit, but keep treats to things like a single sunflower seed or a small piece of unsalted nut rather than packaged products.

A healthy adult Syrian female typically weighs between 130–180g — males are similar. Pick up a small digital kitchen scale and weigh her once a week at the same time of day before feeding. You're looking for a slow, steady decline if she's currently over that range. Equally important is feel: you should be able to feel her ribs with very light pressure but not see them. If she's still round after 6 weeks on measured Harry Hamster and no supermarket treats, it's worth another vet visit to rule out anything hormonal. But in most cases, portion control alone fixes it.