Insight from 10,000 Weight Loss Diets


The RP Diet App has been helping people lose fat and build muscle with custom, AI-generated and adjusted nutrition plans since 2018. Tens of thousands of people use the app every month to help them build, modify, and stick to diet plans, which means that we are accumulating a lot of data on dieting behaviors. To try to learn about what dieting choices and behaviors work best, we took a quick look at a recent cohort of over 10,000 fat loss diets each between six and 12 weeks in duration. These are real diets that real people performed, with, of course, varying degrees of success.

We took a qualitative look at this mass of data and saw what appear to be some interesting trends that we would like to share with you.

1. Shorter diets appears to lead to more success.

We rated diet success by the amount of weight lost on an average completed diet multiplied by the probability that the diet would be completed. It’s no surprise that people lose more weight on 12 week diets than they do on six week diets, but that information alone hides the fact that not nearly as many people make it through a 12 week diet. The longer the diet, generally, the less likely the average person is to follow through to the end (which has been shown previously in diet research).

2.Moderate weight loss paces appear to lead to more success

Many people choose the most rapid weekly weight loss possible, which in the RP Diet App is 1.0% of body weight per week. This means, for example, that a 200 lb person would aim to lose 2 lb per week. The lowest end option for weight loss pace in the RP Diet App is 0.25% of body weight per week (around half a pound a week for our 200 lb example). Looking at the data, it seems that diets closer to six weeks in duration seem to generate the best results at a pace of around 0.6-0.8% body weight lost per week (1.2-1.6 lb per week for our 200 lb example). The longer the diet the better the slower paced loss rates perform. For a 12 week diet, the 0.4-0.6% body weight lost per week range would probably lead to more success (0.8-1.2 lb per week for a 200 lb person). 

It seems aiming to lose about 5.5% of your body weight on a diet is a good choice for success, whether you do that slowly over a 12 week diet or more quickly over a six week diet. The caveat is that it seems like people on six week diets are more likely to finish their diets than those on a 12 week diet. So running two six week diets might be best choice to increase chances of completing the goal!

3. Accepting AI suggestions appears to lead to more success

As you follow the RP Diet App’s AI-generated diet plan, you record your body weight across a week, and at the end of the week, the AI gives you a recommendation and some options. The first option is to accept the AI recommendations (these are generated by the AI’s assessment of how on target you are with your stated goals). The App might recommend increasing, decreasing, or maintaining food intake to keep you on track to your chosen goal. The second option is to make this choice on your own. You can choose to increase, decrease, or maintain food intake against the recommendations of the AI. For example, if the AI tells you that maintaining your current food intake over the upcoming week will keep you on the most likely path to your goal, and you tell the app to reduce food intake instead, you’ve chosen the second (manual) option.

We were very curious to see how the advice our AI algorithms were generating fared and hoped of course that they were effective for users. On the other hand, we allowed the manual overrides because we knew that many of our users would need a diet break or know their body responses to dieting a bit better than the AI. 

Taking a look at average results, it seems that listening to the AI’s suggestions led to more successful diets than manual choices. We considered that this observation was survivor-biased––the people who followed the AI’s recommendations would lose more weight; but all those that tried and failed because the adjustments were too aggressive wouldn’t be counted! It’s like declaring that the Hunger Games have a 100% survival rate by just interviewing the winners! To examine this possibility, we looked at the percent chance of completing a diet based on how many AI adjustment recommendations were taken. It seems that people who accepted more adjustments had higher rates of diet completion than average! People that accepted more AI recommendations just seemed to get closer to their diet goals based on this first pass at the data.

These are early and limited peeks at what makes for a successful diet on the RP Diet App, and we intend to look further into the data with even more dieters as users increase. So far our tentative recommendations based on this qualitative analysis are as follows:

  • Try a shorter diet first. Perhaps a 6-8 week diet, especially if you are newer to structured dieting.
  • Avoid the extremes of weight loss pace. Aim for ~0.5-0.7% body weight lost per week.
  • Follow the plan (shorter diets and more moderate paces should make this less stressful and less difficult!). If the app, the template, or your coach makes a recommendation, it’s probably a good idea to take that input seriously.

Thanks a lot for reading, and we’ll continue to update the app and look at diet results so that we can continue to learn how help more folks become successful! Stay tuned!

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