On Nutrition

Noom, the, “Really, we’re not a diet” app-based weight loss program, first crossed my radar in 2018 or so, about a decade after it was founded. But the program shifted to an object of my attention when one of my clients shared her experience with Noom.

This client had been struggling to overcome binge eating, and found Noom’s marketing language around using “psychology” very appealing. Unfortunately, the restrictive nature of the recommended plan retriggered her binges. “It’s nothing but a glorified calorie counting app,” she told me. “I was so disappointed.” (Noom asks prospective customers a million questions before signing up, but none of those questions are along the lines of, “Do you have, or have you ever had, an eating disorder?”)

Then last year, a professional acquaintance emailed me about an experience with Noom that alarmed her. She’s somewhat of a unicorn: She’s always had an uncomplicated relationship with food and body and had never dieted. But she felt like losing a little weight might improve some joint pain she was having. Noom recommended that she eat 1,200 calories per day, even though she indicated that she wanted to lose weight slowly.

“I only followed it for about a week before I started feeling fatigued and uncomfortable with how it made me feel emotionally,” she said. After quitting, she continued to experience physical symptoms so concerning that she thought she had COVID-19 (she didn’t). It took her about a week of increasing her food intake to feel better.

Rapid weight loss and semistarvation

I decided to do my own sleuthing by signing up for Noom’s free trial. I entered a moderately high weight and a goal weight a few pounds higher than the lowest the program would allow. I claimed that a big vacation in eight months was a “motivator.” Noom immediately informed me I could reach my goal by six weeks past that date, but as I answered additional routine questions, the goal line kept moving until the algorithm decided I would lose the weight by my “vacation” (ta-da!). That meant my fictional persona would lose more than 9 pounds per month — a total loss of 75 pounds and 37% of starting weight — in spite of the fact that I requested “slow and steady” weight loss.

Noom claims it’s not a diet, but let me assure you — it’s a diet. When I tested the food tracker, I saw that I was only allowed 1,200 calories per day, the lowest that Noom allows for women and less than half the calories needed to maintain the starting weight I had entered. (To put this in perspective, 1,200 calories is about what an active toddler needs every day.) I immediately thought of the 1944 Minnesota Starvation Experiment, in which 36 healthy young men existed on half their usual calories — 1,570 instead of 3,200 — for six months, developing food obsession and binge eating, and losing their sex drive.


To cross check Noom’s numbers, I used the National Institutes of Health’s Body Weight Planner. It said losing 75 pounds in eight months would actually require eating fewer than 1,000 calories per day. So, less than what a toddler needs. News flash: Your adult body will eventually fight back if you try to feed it like it’s a 2-year-old.

So how did Noom’s predicted rate of weight loss qualify as “slow and steady”? I discovered that weight loss speed was set to “cheetah” in the app settings. When I changed it to “tortoise,” my allowed calories increased, but I received no alerts that I would no longer reach my “goal” in eight months.

Ditching science for beliefs

Noom heavily promotes its “psychology-based approach,” but the daily short articles on the app are nothing revolutionary. The information is pretty generic and nothing you couldn’t find many other places. The graphics are cute, though.

What disturbed me is the heavy-handed use of the word “believe.” A quiz on Day 1 asks, “What’s the best way to reach your weight loss goals with Noom?” The correct answer? “Simply believe,” because, “If you believe you will reach your goals, you will; if you don’t, you won’t.” This certainly gives the company a convenient out: “You didn’t lose weight on our program? It must be because you didn’t really believe that you could.”

I agree that for things that are technically achievable, not believing you can do it can become a self-defeating prophecy. But that doesn’t mean you can achieve anything because you believe you can. I can’t jump 10 feet in the air, but it’s not because I don’t believe I can. There’s this pesky little thing called gravity.

The reason that most people who intentionally lose weight gain some, most, or all of that weight back within five years — sometimes ending up at a higher weight than they started at — isn’t because they don’t believe, it’s because of basic human physiology. If you are taking in too little energy (because that’s what calories are) your body will become more efficient (your metabolism slows down) to survive on less fuel, and your appetite increases as your body silently screams, “Feed me!” You can’t “Little Engine That Could” your way to long-term weight suppression.

Of course, the motivational rhetoric is about weight loss, not sustainable weight maintenance. Noom heavily promotes a 2016 study of 36,000 participants who used the app consistently for at least six months — a fraction of the more than 10 million people who had downloaded the Noom app at the time of data collection. The study found that 77% of these participants lost weight while using the app, but there’s no record of what happened after that for 21,000 participants. As for 15,000 participants who were followed longer than six months, only 23% lost at least 5% of their starting weight and kept it off — 10% of the original 36,000. That paints a very different picture.