I asked ChatGPT to build me a workout plan for a bigger butt

ChatGPT can do a lot. It can create playlists, help with house hunting, interpret and analyze data, assist in writing and editing, code, and even play games. Can it also be your personal trainer and dietician?

I asked OpenAI's chatbot to train me. For a full month, I followed its diet restrictions and workout regime, asked it questions along the way, and discovered the chatbot's biggest deficiencies — and most impressive abilities when it comes to fitness.

How I used ChatGPT as my personal trainer

I sent the free version of ChatGPT my request: a detailed, daily exercise and diet plan that spanned four weeks. I gave the chatbot my weight, height, geographic info, current fitness levels, any necessary medical conditions or injuries, and the kind of access to workout equipment I have (a gym membership at Blink, an outdoor running space, and boutique fitness classes near me). I told it that my main fitness goal wasn't to lose weight but to build a firmer butt. As I describe it to my friends: I want NASA to confuse my ass for a new landmass when it looks at Earth from space.

"Sure, I can help you create a 4-week fitness plan to help you achieve your goal of getting a larger, firmer butt," ChatGPT told me. "However, please keep in mind that everyone's body is different, and results may vary based on various factors like genetics, diet, and consistency."

It sent me the first two weeks of the plan, and then stopped generating more info, so I had to prompt it to send me the next two weeks. The exercise plan we landed on switched between workouts at the gym, rest days, light cardio, and runs outside. Here's an example of a typical week:

Monday:

Warm-up: 5-10 minutes of jogging or jumping jacks

Weighted Squats: 3 sets of 10 reps

Walking Lunges: 3 sets of 10 reps per leg

Leg Press: 3 sets of 10 reps

Romanian Deadlifts: 3 sets of 10 reps

Glute Bridges: 3 sets of 10 reps

Cool-down: 5-10 minutes of stretching

Tuesday:

Rest day or light cardio

Wednesday:

Warm-up: 5-10 minutes of jogging or jumping jacks

Bulgarian Split Squats: 3 sets of 10 reps per leg

Cable Kickbacks: 3 sets of 10 reps per leg

Barbell Hip Thrusts: 3 sets of 10 reps

Dumbbell Step-ups: 3 sets of 10 reps per leg

Leg Extensions: 3 sets of 10 reps

Cool-down: 5-10 minutes of stretching

Thursday:

Rest day or light cardio

Friday:

Warm-up: 5-10 minutes of jogging or jumping jacks

Smith Machine Squats: 3 sets of 10 reps

Side Lunges: 3 sets of 10 reps per leg

Sumo Deadlifts: 3 sets of 10 reps

Cable Pull-throughs: 3 sets of 10 reps

Donkey Kicks: 3 sets of 10 reps per leg

Cool-down: 5-10 minutes of stretching

Saturday:

Rest day or light cardio

Sunday:

Outdoor run: 30-45 minutes at a moderate pace

It told me to eat around 2,000-2,200 calories a day and to consume 165 grams of protein daily. This is considerably more protein than I usually eat — roughly 120 more grams a day. I was vegetarian for many years, but recently started eating meat to meet protein goals (you can definitely meet protein goals without meat, I simply struggle with it). When I would ask ChatGPT for recommendations, it gave the typical advice — chicken, turkey, beef, fish, eggs, Greek yogurt, cottage cheese, protein powder. All of these are helpful ideas, but they didn't actually make meeting my protein goals easier.

Everything ChatGPT told me came with some kind of warning to save its own butt. When it gave me a routine, it added at the end that specific exercise and diet needs are going to vary and that, ideally, you'd be able to consult with a registered dietitian and personal trainer.

So I reached out to Crystal Zabka Belsky, a registered dietitian and medical nutritionist, who prepped me on the pros and cons I'd likely see during my experiment. I asked her about how the ChatGPT diet was so far away from my typical diet, and she recommended using a food delivery service, like the one, coincidentally, she works for — Clean Eatz. And, to be fair, the Clean Eatz food was pretty good, and having prepared meals in my home was definitely helpful for the calorie- and protein-counting necessary to stick to ChatGPT's guidelines.

I asked ChatGPT the best way to measure success in this experiment, and it told me to take progress photos, body measurements, assess my strength and endurance gains, gauge how my clothes fit, and use a body fat percentage calculator.

"Remember that progress can be slow and may not always be visible on the scale," the chatbot told me. "It's important to celebrate small victories along the way and focus on overall health and wellness rather than just physical appearance."

The results: I lost a couple pounds, gained an inch on my glutes and lost an inch on my waist. Pretty good, even though I only did the plan for four weeks which isn't enough to see long-term goals reflected. The physical results don't really matter to me as much as the process, though. For this experiment, I was focused on other results: Was ChatGPT a useful tool? Did it help me more than a simple Google search? Did it provide the kind of assistance I really need from a personal trainer?

Why I loved using ChatGPT as a personal trainer

First of all, it is free, convenient as hell, and always accessible. Most personal trainers and dieticians can't answer a question from a client at two in the morning, but ChatGPT can. And it's travel friendly — if you leave the country or state, like I did for a few days, you can take ChatGPT along with you.

Belsky, the dietician I spoke to for this piece, said that "it offers a sense of accountability and access for highly motivated people." I would not describe myself as "highly motivated," which might be why I didn't experience any kind of accountability from the chatbot, but if you're using ChatGPT as a free fitness resource, or following any sort of plan you find online, then some will power is involved.

ChatGPT also has a pretty massive knowledge base, so I felt comfortable — whether I should have or not — following its advice.

Why I won't use ChatGPT as a personal trainer again

My main complaint is that, despite having considerably more information about my health than, say, Google, its feedback is still far too vague. For instance, I got a cold during the workout plan and asked if I should take time away from the workout plan or alter my diet. It said that it is "generally recommended" to rest and avoid exercise while I'm sick, which is helpful, but I would have preferred something more specific that I might get from an actual, real-life personal trainer. Tell me how many days I should rest, or if I should stop doing cardio but continue lifting, or if I should modify my diet to prioritize vegetables. Instead, I received a generic response that was on par with what Google tells you.

At the time, there wasn't a ChatGPT app, either, which means while I was at the gym, I had to use the browser to ask it questions. This isn't a deal-breaker but, my God, it was annoying.

ChatGPT is a fully text-based AI model, so it can't send any images — an unfortunate issue considering I needed to know detailed information about the kind of form I should have while working out. Usually, I'd watch a YouTube video to check my form. For instance, the chatbot gave me multiple different kinds of deadlifts to do during the week but, honestly, I don't know the difference between any of them. It would describe the differences to me when I asked, but I could never be sure. That kind of in-person, in-the-moment feedback on form really helps. Furthermore, I had been lifting on and off for years, so I know how much weight to use, but I could see that being a difficult decision to make for some folks, and ChatGPT was almost no help at all when trying to figure that out.

Finally, it was a huge challenge for me to meet the protein goals set up by ChatGPT. And Belsky told me that because ChatGPT doesn't recommend what time of day you should be consuming the protein, it won't be as effective as it could be.

"It's not telling you [how] you should be dosing the protein every so many hours all day to maximize protein synthesis," Belsky said.

ChatGPT is helpful and free if you’re looking for a starting point, but it lacks the detailed personalization needed to reach very specific goals. Overall, the cons far outweigh the pros for me. So, no, ChatGPT cannot be your personal trainer.