In one way, you are correct about summer weight going faster. But it's got more to do with the amount of sunlight than the temps. Your pituitary is stimulated by longer daylight hours and intensity of the exposure. As the master gland, the pituitary influences the functioning of every other organ and your endocrine system, including your thyroid. You may think it's all in your bikini mind, but I think it's more in your summer-lighted brain!