Fat rats may be adorable and squishy, but just like with humans, letting your rat get too overweight can shorten its lifespan and degrade its quality of life.
Fat rats can develop heart problems, diabetes, and mobility issues that limit their ability to climb around their cage and enjoy their play time.
Just like with humans, overeating too many fatty foods and carbs causes obesity in rats! This combined with a lack of exercise can cause rats to pack on the extra pounds (well, grams!)
Here’s how to tell whether your rats are at a good weight, and some tips for how to help them lose weight if needed.
How much to feed your rats
Each rat is a little different. Even different cage mates can sometimes have different weights. Pay attention to your rat’s weights over time and adjust their diets and snacks accordingly.
A lot of new rat owners overestimate how much they need to feed their rats. Keep in mind that your rat is much smaller than you are, so it’ll be satisfied with a lot less food!
A good rule of thumb for how much to feed is to start with a handful of dry food a day for each rat, then adjust as needed. Lab blocks and/or a fresh diet of fruits and vegetables is usually preferable to seed mixes, which can be too fattening for rats. For a detailed guide on diet, see What do Pet Rats Eat?
If you have multiple rats, try spreading the food out across the cage so that they can search for it independently. It keeps them enriched and that way your most dominant rat doesn’t hoard the food.
If one rat is elderly or sickly, you may have to separate them from the group to feed them so they get enough.
How to weigh your rats
You don’t really need to weigh your rats, but if you like to get scientific, you can use a kitchen scale.
- Put a container on the scale, like an empty yoghurt container.
- Zero out the scale with the empty container on top.
- Place your rat inside of the container.
- If you like you can give the rat a little treat to keep it occupied.
- Read the scale and record your rat’s weight somewhere.
Weighing your rats once a week or every two weeks can help you monitor their weight over time, and alert you if something’s wrong.
What is a normal weight for rats?
Male rats can weigh anywhere from 450g to 1kg! There’s quite a lot of size variation between different males. Healthy female rats typically only weigh around 300-450g.
Rats can vary quite a lot in size just from genetics. Just like us, some rats are naturally more prone to obesity than others. It also depends on their mobility as they age and activity level.
Signs of Obesity in Rats
It’s sometimes more helpful to “eyeball” your rat than to weigh it. You will notice signs like these:
- You can see a bulge in their belly from above. Their belly may be round and protrude out from the sides.
- Their spine is not clearly visible when you part the fur on their back.
- The rat has difficulty moving, climbing or jumping. Healthy rats are agile and have no difficulties navigating their cage and their play areas.
- Obese rats often waddle from side to side when they walk.
- Severely obese rats sometimes even have “rolls” of fat.
- The hind legs splay out to the sides when the rat sits.
Helping rats lose weight
It can be harder to help rats lose weight than to gain it (especially if you feel guilty about giving them less treats!)
The Fat Rat Diet
You may have to start measuring out your rats’ daily diet so that you can track the changes more closely. Give them slightly less food at their daily meal times. Small diet changes from week to week can help them adjust without feeling too hungry.
As hard as it is, try to avoid giving your little friend extra treats on top of their usual dry and fresh food, at least until they lose some weight.
You can also try avoiding fattier foods like nuts and seeds, avocados, chicken and other meats for the time being.
Exercise
You could offer your rats an exercise wheel inside of their cage. (Make sure it’s large enough for rats!) Some rats like exercise wheels more than others, so you might have to help them understand how to use it.
Give your rats lots of time outside their cage to run and explore around your house. You can encourage them to exercise by playing games with them. You could design agility courses or mazes for them.
Swimming can be a great exercise that’s gentle on the joints if your older rats suffer from mobility issues as well. Not all rats love swimming, but if yours do, it’s a great activity! Adding treats like peas and corn to the water can encourage your rats to dive in. Just consider how many you’re feeding them in relation to the rest of their fresh veggies for the day. Make sure to monitor your rats while they play in the water!
You could also try giving your ratties a deep digging box with dirt or a different type of substrate than they normally use in their cage. Many rats love digging and will get super enthusiastic about it!
Are some rats more prone to obesity?
Yes! One study found differences between two strains of lab rats: Diet-induced obesity in animal models: points to consider and influence on metabolic markers | Diabetology & Metabolic Syndrome | Full Text
Although not all domestic rats are related to lab rats, we can probably assume that rats with different genetics may have a harder or easier time putting on weight.
If you have multiple rats and find that one is gaining or losing weight moreso than the others, you can try feeding them separately to make sure they’re getting the right amount of food for their metabolism.
How long do obese rats live?
Rats generally live between 2-3 years. Obesity in rats can cause health problems like heart disease, diabetes, and arthritis. It can also weaken their immune system, making them more vulnerable to infections. These conditions can shorten the lifespan of an obese rat compared to a healthier cage mate.
Conclusion
We all love our little friends and want them to be the healthiest they can be. Through attention to your rats’ weight, diet and exercise, you can contribute to your pets’ overall well-being, extend their lifespan, and ensure they can enjoy an active and fulfilling life!