Should Rats Be Free-Fed or Calorie Restricted?

As any rat owner knows, rats are prone to obesity, particularly older male rats. However, being omnivores and foragers, they seem most content with free access to as much food as they like. It’s hard to bring oneself to restrict a rat’s diet. They only need about 60 calories per day to maintain a healthy weight, but will gladly beg for more. Some rat owners feed a restricted calorie diet and say their rats are healthier and slimmer for it. Others free feed and argue that their rats are happier and more active with the opportunity to forage all day.

Arguments for Free Feeding Rats

Most current rat care guides and books will advise owners to allow rats access to food and fresh water at all times. While free access to water is an absolute necessity, there is some debate regarding food. Owners who free-feed point out that, in the wild, rats would not eat scheduled meals. They would eat bits and scraps of food, storing what they can’t eat for later. This foraging behavior keeps wild rats active and means that something is always being digested, rather than a big pile of food being dropped into the digestive tract all at once.

In captivity, free feeding allows rats to stash food for later, a favorite behavior of many females. This amusing routine often involves taking each individual piece of food from a bowl and moving it elsewhere. Free feeding also ensures that no single dominant rat can prevent less dominant rats from accessing the food bowl.

Arguments for Calorie Restriction

Scientific studies have shown that calorie restriction leads to longer lives  in laboratory rats. The problems of obesity, including heart and liver disease, act as a significant detriment to the health of rats permitted to become fat. In addition, wild rats would be unlikely to find enough food to simply eat all day. Domestic rats don’t forage actively as wild rats do, and need fewer calories to maintain their more sedentary lifestyles.

Rats that are bored due to a lack of free choice food can be entertained with toys and playtime outside their cage, which also helps to socialize and exercise them.

The Bottom Line

A calorie restricted diet is probably better for rats in the long run. If you feel guilty about restricting calories, you can give the rats’ daily allotment of blocks one at a time or hang them from the top of the cage so that it seems like a bigger reward to get a single lab block than it would if the blocks were offered in a bowl. However, if you just can’t bring yourself to feed your rats less, exercising and playing with them outside of the cage can counteract most detrimental effects of overeating.

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