1. Low activity level and sedentary lifestyle
Thee number-one cause of obesity in cats, without a doubt, is a sedentary lifestyle. You probably already know that there is one simple equation that can explain weight gain:
Calories stored in fat = Calories consumed − Calories spent
If your cat spends fewer calories than he actually consumes every day, the excess is stored for, as nature dictates, times when mice aren’t as abundant. Unfortunately, in household situations, the day of fewer mice never comes. The bowl is always full, and the only activity a cat has to engage in to fill it is to meow.

The sad truth is that cats do not spend nearly as many calories as they used to. We love having our cats live indoors, but this, unfortunately, leads to a reduced amount of exercise. This is simply because cats turn into couch potatoes, and their activities become dependent upon their humans’ involvement.
Solution: get an interactive toy and play with your cat for 10 minutes at least twice daily, preferably before you provide your cat with a meal. This bare minimum will surely go a long way. If you’re ready to be more creative − and we love people who are creative − here is a list of 11 ways to have fun with your cat.
2. Overfeeding
While low activity is one of the biggest problems indoor cats face nowadays, a second problem is that cats eat − or, to be more precise, are fed − too much. There may be several occasions in which cats might receive too much food:
- Free feeding, which usually means filling the bowls and then adding more when they are half empty, is a common contributor to obesity in cats. There are so many problems with giving free food access to your cat, but the biggest problem is that eventually your cat will eat too much because you can’t control how much your cat eats. This is especially true if you have more than one cat.
Feeding too much is the second most important contributing factor to obesity in cats. - Too much food. Again, this is very similar to free feeding. Even if you provide food to your cat in meals, do you weigh out his daily required amount and feed accordingly? Seriously, read the label on package and measure out the lowest amount necessary for your cat’s ideal (not current) weight, and feed no more.
- Treats and table scraps. It’s totally okay to give some treats to your cat if he or she enjoys them. Treats are also necessary if you are training your cat. Continue providing them, but subtract the corresponding amount from your cat’s daily food intake.
- Not considering activity changes at a certain age. Most cat owners know that their cat will become less active as he matures. Kittens play a lot, while adults are aloof. But did you know that your cat’s energy requirements are reduced slightly from year to year, and, basically, you should slightly lower the amount of food you provide to your cat over the years? As a senior, a cat may require up to 20% less food than he did as a young adult.
- Not reducing the amount of food after neutering or spaying. There’s a common cat myth that neutering causes obesity in cats. In reality, neutering and spaying do not cause obesity. However, there’s no smoke without a fire, right? Neutering significantly reduces your cat’s activity level, which is understandable − no sex drive, no need to run “who knows where” − so energy requirements also decrease. What you need to do, then, is either feed less or initiate more activity in your cat.
3. Poor diet – too much fat and too many carbohydrates in the food
While this is not among the most common causes, eating junk food, just like in humans, causes obesity. But what is junk food for cats?
In nature, cats eat live prey, some insects, and maybe a few blades of grass. This is a diet that is mostly rich in protein, moderate in fats, and with virtually no carbohydrates. What do most commercial, especially dry, foods consist of? Moderate protein, slightly higher fat, and a large amounts of carbohydrates.
Good cat food:
- Contains identified meat as the first ingredient
- Contains high amounts of protein, a moderate amount of fat, and almost no carbohydrates
- Contains no or very little grain
- Check here for other properties that a good cat food should have
So, if you don’t feed junk food to your cat, his weigh will drop, guaranteed!
4. Medical problems can also cause obesity in cats

Last, but not least, there are several medical conditions that cause cats to become overweight or obese. The most common of these are Diabetes Mellitus, hypothyroidism, and hyperadrenocorticism.
There are other, less common diseases as well, so this is why you should visit a veterinarian if your cat is obese. If your cat is ill, putting your cat on a diet without treating the medical cause will only make him suffer.
The causes mentioned above are the most common causes of obesity in cats. Sometimes cat owners tell us that they are proud of their cats being “plus” size and/or that it fits their personality. But is it really that cool? Find out here.
This article is a part of series about fighting obesity in cats.