Here's why:
* Different species, different sizes: Guinea pigs are significantly larger than hamsters. Even a healthy hamster can be smaller than a young or smaller guinea pig.
* Breed differences: There's a wide range of hamster breeds, with some being naturally larger than others.
* Individual variation: Even within a breed, hamsters can vary in size.
* Obesity isn't just about size: A hamster can be obese even if it doesn't appear "huge." Obesity is about body fat percentage, not just overall size.
How to tell if your hamster is obese:
1. Feel for their ribs: You should be able to feel their ribs easily without pressing hard. If you can't feel them, or they are very difficult to feel, it's a sign of excess body fat.
2. Look for a "pot belly": Obese hamsters often have a rounded abdomen that sticks out noticeably.
3. Check their activity level: An obese hamster might be less active and more sluggish than a healthy one.
4. Consider their diet: A diet high in treats and unhealthy foods can contribute to obesity.
If you suspect your hamster is obese, consult a veterinarian. They can assess your hamster's weight and body condition and provide advice on how to help them lose weight safely.