Washington - With two popular diet drugs pulled from the market Monday because of concerns about heart complications, obesity specialists said yesterday that there are few substitutes and predicted that consumers will continue to demand research on alternatives.

The search for weight loss medications is likely to come under closer scrutiny by regulators and consumer watchdogs in the wake of the recall of dexfenfluramine, which is sold as Redux, and fenfluramine, sold as Pondimin. Fenfluramine is one-half of the diet drug combination known as "fen-phen."