go on a diet

go on a diet

To begin a specific nutritional plan typically consisting of eating smaller amounts of food, eating (or avoiding) particular foods, or both in an attempt to lose weight or achieve some other health benefit. I think I need to go one a diet—I'm actually having trouble going up and down the stairs without losing my breath! My doctor suggested I go on a diet rich in red meat and leafy greens for a month to try to bolster my iron levels.
See also: diet, on