Feast/Fast! Is that a healthy way to lose weight?

Feasting/fasting as a weight loss strategy is in the news. People are sharing their success following a weight loss plan that calls for fasting two days of the week and feasting the other five.

That’s the simple principle the 5:2 Diet plan embraces. It’s been proven to work and before you dismiss it as “unhealthy” you should know there is some sound research that suggests otherwise.

The first thing I need to do is define what feasting on the 5:2 diet plan means. It’s not a “free-for-all, throw-caution-to-the-wind, eat-everything-in sight, go-for-broke, pigout!

It’s eating roughly 2000-2200 calories or what may be described as a “normal diet.” There are no “forbidden foods.” You can eat what you like. The best part about this plan is enjoying your meals and snacks without feeling guilty.


Just as the feast days are better described as simply eating normally, the fast days are not really fasting, as in taking in nothing but water. On the two fasting days, followers limit their calories to 500.

From what I’ve read, if people following this plan use some common sense with their food choices on the feasting and the fasting days, this approach to weight control is healthy. Moreover, there is some reliable, scientifically sound research that suggests it’s a very healthy way to manage weight and even offers its followers some added health benefits by intermittent fasting.

As with any weight loss plan, there are some caveats. With the 5:2 plan the biggest drawback is for people who have a hard time sticking to the fast days and/or far exceeding what’s considered normal on the feast days. There is some discipline needed to manage both the feasting and the fasting days.



The good news is fasting is only 2 days out of the week and it’s not a complete fast. If smart choices are made, it’s entirely possible to get through 2 days a week feeling totally deprived on 500 calories.

It’s not a secret that I work for Weight Watchers. It’s not a secret that I lost 40 pounds about 25 years ago following the Weight Watchers plan (to the best of my ability; my adherence was not even close to 100%) and that I still loosely follow the plan to maintain my goal. Based on that, it might surprise you that I’d endorse this plan for some people, but not everybody.

If you are considering trying this method of weight loss, there are some things you should know, starting with knowing yourself. I know that I lack discipline and given too much rope, I’ll hang myself. I am an honest person except when it comes to telling the truth to myself. I tend to lie to myself – a lot if I’m not careful. I need some outside accountability to lose weight and even to maintain.

If you’re like me, here are the ways 5:2 diet could go wrong.

  • I might eat too much on the “normal” days, especially if I did a good job of adhering to the 500 calorie fasting days.
  • I would make a stupid choice on the fasting day and be unable to limit my calories to 500. I might begin my fasting day with a 500 calorie piece of cake and tell myself, “nothing else to eat until tomorrow.” By the time dinner rolls around I’d be turning “today’s fasting day into a normal day and promise to fast tomorrow.” Tomorrow would never come.
  • Everyday would start out a fasting day and end as a normal day and I wouldn’t lose weight. My normal days might even be a little, mmmm well, normal, and I’d gain weight!


If I wanted to make 5:2 work for me as a weight loss plan, I’d need the accountability and structure of Weight Watchers meetings. Even though I would not be following the plan or even the least bit concerned about points, the weigh-in would give me the accountability I need. The focused conversations around managing eating with a focus on healthful choices would support my sticking to 500 calories on the 2 fasting days.

I know anybody could get a weigh-in and a meeting discussion cheaper by doing something like TOPS (Taking Off Pounds Sensibly). I like the professionalism of the Weight Watchers staff. I like that the leaders are trained to guide meetings without running the whole show or wasting my time with a monologue all about themselves. I further appreciate that they know how to gently dissuade a member who tries to take over the meeting. Indeed that’s part of my job ensuring that the people who work in meetings give every member excellent, neutral, non-judgemental service and accurate, scientifically sound information. 

I certainly appreciate that Weight Watchers doesn’t do things such as recognize the “biggest losers of the week and the month.” Losing weight isn’t a competitive support. Group support isn’t trying to lose faster than everybody else in the group. The biggest benefit of Weight Watchers is an environment of group support in which members learn about themselves and how to align their habits with their weight-related goals.

Yes, Weight Watchers has a food plan. No, nobody gets banged over the head or publicly shamed if they don’t follow it, even though US News and World Reports rated the Weight Watchers food plan as the best weight loss diet for the fifth straight year in a row.

US News and World Report has also ranked 5:2 Diet Plan (they list it under The Fast Diet). Here is how it ranked out of 38 diets tested.

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If you’re doing the 5:2 Diet or some form of a feasting and fasting diet, I’d love to know how it’s working for you. Please consider sharing your observations in a comment!

Jackie Conn

About Jackie Conn

Jackie Conn is married and has four grown daughters and four grandchildren. She is a Weight Watchers success story. She's a weight loss expert with 25 years of experience guiding women and men to their weight-related goals. Her articles on weight management have been published in health, family and women's magazines. She has been a regular guest on Channel 5 WABI news, FOX network morning program Good Day Maine and 207 on WCSH.