Cats are not carbon copies of each other any more than people are. You can't get a large group of people to weigh the same amount by putting them on the same diet, I don't see why cats would be any different. And, as with people, I'm sure some are genetically prone to weigh more, have a harder time losing weight, and have to have a more strictly controlled diet to lose weight and maintain the weight loss. And the same with weight gain in thin people and thin small boned cats.

With people we are learning that people with certain genetic profiles don't have higher disease risk at above-average weight levels, again, that is likely true with certain cats. However is it also likely true with both cats and people that this situation accounts for only a percentage of the overweight cats and overweight people, that the majority ARE overeating for their activity level and are at higher risk of certain diseases because of this. While certain research is illegal with people, with cats I believe they know the disease risk is true because researchers are allowed to deliberately overfeed cats to induce diabetes and other illnesses and from what I've read have done these types of studies.

I hate to disagree with a vet school attendee but I do. There is no standard regulation of what LIGHT food means across the board - all it indicates is that with two foods of the same type (adult, senior...) by one manufacturer, the food saying LIGHT has to have a bit less fat than their REGULAR. One manufacturer's LIGHT food might have more fat and/or kcals than every other manufacturer's REGULAR food of that type so a person changing to that LIGHT food could actually cause weight gain in their cat.

Regulation nutrient requirements only take into account the nutrients a cat needs to survive, not to be in excellent or even very good health. It is fairly well known that some light foods (especially prescription) lessen the quality of the cats' coat due to the loss of fats in the diet. And overall then, what does this say about the nutritional requirements of pet foods if there is no difference in a cat fed regular food for a lifetime or light food for a lifetime? Is your vet school saying that the regular food really has too much fat and the nutritional regulations for regular foods are wrong? Or are they really saying the lack of regulation causes there to be so little difference in the foods that it doesn't matter? In which case why would vets be recommending one over the other?

Bottom line in my opinion is that LIGHT foods are a mostly unregulated marketing gimmick with a corporate goal of maintaining profits by stopping owners from cutting down their daily food servings and buying less cat food.
HEY, YOU DON'T NEED TO FEED LESS FOOD, JUST GET OUR LIGHT BRAND AND YOU CAN KEEP SERVING THE SAME AMOUNT, OR EVEN MORE FOOD!! They are specifically designed to allow owners to continue to feed their cat a greater quantity of food than it needs. Again, how is it in the best interests of cats for vets to recommend this practice if the LIGHT food really works?

This is all why makers of high quality foods do not produce LIGHT formulas. Standard pet food LIGHT formulas are produced with the same wonderful corporate thinking that gives us the new Hostess LIGHT Cupcakes, Jello LIGHT Pudding, etc., both of which are sold at the corner store in my neighborhood. Yay, I can eat Hostess LIGHT Twinkies for many years and they will be good for me!!! <g>