Though an occasional short paragraph is fine, particularly if it functions as a transition or emphasizes a point, a series of brief paragraphs suggests inadequate development. How much development is enough? That varies, depending on your purpose and audience.

For example, when she wrote a paragraph attempting to convince readers that it is impossible to lose fat quickly, health columnist Jane Brody knew that she would have to present a great deal of evidence because many dieters want to believe the opposite. She did not write the following.

SKIMPY PARAGRAPH

When you think about it, it’s impossible to lose—as many diets suggest—10 pounds of fat in ten days, even on a total fast. Even a moderately active person cannot lose so much weight so fast. A less active person hasn’t a prayer.

This three-sentence paragraph is too brief to be convincing. But the paragraph that Brody in fact wrote contains enough evidence to convince even skeptical readers.

DEVELOPED PARAGRAPH

When you think about it, it’s impossible to lose—as many . . . diets suggest—10 pounds of fat in ten days, even on a total fast. A pound of body fat represents 3,500 calories. To lose 1 pound of fat, you must expend 3,500 more calories than you consume. Let’s say you weigh 170 pounds and, as a moderately active person, you burn 2,500 calories a day. If your diet contains only 1,500 calories, you’d have an energy deficit of 1,000 calories a day. In a week’s time that would add up to a 7,000-calorie deficit, or 2 pounds of real fat. In ten days, the accumulated deficit would represent nearly 3 pounds of lost body fat. Even if you ate nothing at all for ten days and maintained your usual level of activity, your caloric deficit would add up to 25,000 calories. . .. At 3,500 calories per pound of fat, that’s still only 7 pounds of lost fat.

—Jane Brody, Jane Brody’s Nutrition Book