25 of the most extreme and dangerous weight-loss methods

The grapefruit juice diet
This fad diet did the rounds in the 1930s. Dieters were expected to severely curb their food intake to 1 000 calories (4 184 kilojoules) per day, and every meal should be accompanied by either half a grapefruit or 230ml freshly-squeezed grapefruit juice.
Why it’s dangerous: While there’s no serious harm in the grapefruit juice itself, it’s the extreme reduction of kilojoules that makes this diet a fad. And grapefruit can clash with medications such as blood thinners.