Eat less, move more. These words have been the cornerstone of diet advice for decades, leading millions of Americans to greet the new year with vows to cut calories and hit the gym. In all, one in five U.S. adults are dieting at any given time, according to the international market research firm The NPD Group, and 57 percent would like to lose 20 pounds or more. Yet few will reach that goal.
There is little agreement about the optimal levels of iodine people need. The U.S. Department of Agriculture maintains that we need 150 micrograms a day, but iodine advocates are quick to point out that a person eating a typical Japanese diet (where hypothyroidism, or low thyroid activity, is rare) ingests 12.5 milligrams of iodine each day—83 times the amount recommended by the government.