Meal replacement shakes are more likely to work when you feel full and satisfied after you drink them. If you drink a shake and then feel hungry 20 minutes later, it can be hard to wait for your next meal, and you may end up reaching for a candy bar or another high-calorie snack to supplement the shake. This is why they do not work for some people.
Because shakes and other dietary supplements can’t provide the same quality of nutrition as whole foods, dietitians and physicians typically recommend that people use them only on a short-term basis. That means even if you lose weight during the time you use shakes as meal replacements, you may gain some of that weight back when you return to your regular diet.