Dr. Frank Field is the affable NBC (New York) weatherman and general science correspondent whose month-long diet was a well-publicized addition to the nightly news. In his usual cordial manner, Frank outlines the off-stage particulars (family comments, specific menus and recipes) and related tidbits (shopping hints, exercise values, Tom Snyder's asides) which enabled him to lose sixteen pounds. The diet itself was nothing remarkable--less meat, fats, carbohydrates--and the slightly padded book offers little that veteran dieters haven't stumbled on already. The slant here: Frank's sweet tooth, which was assuaged during the siege with artificial sweeteners in a variety of guises--a dessert apple baked in diet cherry soda, or a whipped topping with a skim milk base. Some of the other adjustments are more palatable--Salade Nicoise, sans potatoes and olives--but beware of pretenders: bread dipped in egg and then broiled passes for French toast, with powdered sweetener for garnish.