1. Could "Diet Water" be making me gain weight?
2. Is there any help for perimenopausal fat?
3. Are omega-3 pills a waste of time?

Could "Diet Water" be making me gain weight? After hearing for years that drinking water is an easy way to slim down, I started drinking H20 with a calorie-free flavor mix stirred in; It tastes better than plain, so I’ve been downing a ton. I was so proud, until I realized I’ve put on four pounds! How could this be?

Water is proven to curb appetite, rev metabolism and flush pounds of stagnant waste from the colon, but that diet mix may be spoiling your results. Such products often contain artificial sweeteners like aspartame or sucralose, which are linked to a 41 percent increased risk of weight gain. That’s because they trigger high blood sugar, leading to fat storage. Try switching to a zero-calorie mix-in with no artificial sweeteners like True Lemon, True Orange or True Lime ($20 for 192 packets in assorted flavors, at amazon.com). Bonus: These mixes deliver 25 percent of the daily value of fat-burning vitamin C.

Is there any help for perimenopausal fat? Turning the big 4-O has me paying more attention to what I eat—I don’t want to gain 50 pounds like my sister did during perimenopause. So this summer I ate tons of fruit like watermelon and oranges, and I had a spinach-and-tomato salad just about every night. But I still gained! What went wrong?

Women in their late thirties and early forties experience a thyroid slowdown caused by hormonal flux. Progesterone levels fail too low, so estrogen becomes dominant, which in turn hinders thyroid-hormone production. That alone causes weight gain, and unfortunately your healthy diet may have added to the problem. The culprit: a contaminant called perchlorate that can lurk in water-laden fresh fruit and veggies (like watermelon, citrus, tomatoes and spinach). Perchlorate hinders iodine uptake in the thyroid, making the organ even more sluggish. To offset these effects, flavor meals with iodine-rich seaweed seasoning—I like Eden Organic Seaweed Gomasio ($3 for 3.5 oz., at EdenFoods.com). Also, a progesterone cream (like ProgestaKey, $37 for a two month supply, at unikeyhealth.com) can keep hormones balanced and stop estrogen-induced thyroid slowdown.

Are omega-3 pills a waste of time? I’ve been taking an omega-3 supplement for months, and the benefits have been amazing: I’ve lost 9 pounds and my mood has lifted. But when I told my doctor about it, he said it’s likely a placebo effect since omega-3s only help if you don’t eat any bad fats. Is that true?

To a degree: For people who consume lots of trans fats and omega-6 fatty acids, there is evidence that omega-3 fatty acids are less likely to be used by the body. But in my experience, most health-conscious women don’t consume unhealthy fats to the extent that the omega-3s are rendered useless—and omega-3s do seem to be working for you. That said, continue to be vigilant about cutting trans fats (listed on labels as partially hydrogenated oils, hydrogenated oils and vegetable shortening). And try to eliminate corn and sunflower oils to reduce omega-6s. Then strive for 1,000mg to 3,000mg of omega-3s daily, like those in flaxseed and fish oil (note: Omega-3s thin the blood, so use caution if you’re on blood-thinning meds).