Calories vs weight loss question

So we have a client who is feeding her cat Kirkland Signature Cat food, she said it is about 398 calories per cup, she is feeding her 12# cat 1/4 cup per day which is only about 98 calories per day, the cat is gaining weight.  The vet of course wants to put it on Science Diet's Metabolic and have her increase the amount she is feeding to 5/8 cup per day it has 289 calories per cup.  She said that if they aren't getting enough calories they will hold onto their weight.  The owner said she used to feed the cat more, but that's about all it eats, it doesn't act hungry or anything.  So has anyone heard that if they aren't getting enough calories they will gain weight?  I talked to her about canned food and sent her the catinfo link on obesity.

Could it be hypothyroid?

molldee said:

Could it be hypothyroid?

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That's a possibility although Hypothyroid is pretty rare in cats. 

Hypothyroid usually occurs in cats that have been treated for hyperthyroidism. The treatment brings the thyroid function down below normal.

cprcheetah said:

So has anyone heard that if they aren't getting enough calories they will gain weight?  I talked to her about canned food and sent her the catinfo link on obesity.

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That's not possible - to gain weight on fewer calories than WERE maintaining weight unless there has been a metabolic change. If blood work hasn't been done VERY recently, kitty's organ functions need to be checked. And if this wasn't suggested by the vet, then a new vet needs to be considered.

The issue here is gaining weight. Just like people, cats can go into "starvation" mode, where their metabolism adjusts to the amount of food fed - but this will maintain weight, not cause them to gain weight.