Weight Watchers, founded in the 1960s by Jean Nidetch, is a company offering various dieting products and services to assist weight loss. It started as a discussion group for how to best lose weight.

Weight Watchers offers two programs: A program called FlexPoints and one called CORE. With FlexPoints participants are assigned a target point value to meet each week. Foods have a points value (created from a patented algorithm taking into account calories, fat, and fiber), which is added to the participant's week point value when eaten. With the CORE program the participant is allowed to eat a limited number of foods in the amount required to reach their comfort level of fullness. Both programs require a minimum consumption of milk products or milk substitutes per day. The participant is able to make a choice between the two programs. For both programs exercise earns activity points, which can be left as is or swapped for food; 35 free activity points are also given at the start of the week.

Weight Watchers in the UK, Slimming World's main competitor, even advertises under the slogan "where no food is a sin" in reference to Slimming World's giving some food "sin" values.