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Can you build a bigger butt without squats/deadlifts? This was a 90-day glutes workout experiment with one constraint. Tahnee has trained for years, but five years ago, she hurt her back doing heavy squats and felt like she’s now got a flat butt. So we set rules and ran the challenge.
The 90-day glute workout experiment. Tahnee — No squats, no deadlifts, and no heavy loading on her spine. Me — Train however I want. The bet — If Tahnee outgrows me, I go vegan for 30 days
We built the plan around four glute movement patterns for well-rounded glutes growth:
1. Lower body press — Glute-dominant step-up/step-down
2. Lower body hinge — Single-leg dumbbell deadlift/single-leg RDL
3. Squeeze — Barbell hip thrust, staying glute-focused at the top and avoiding overextending the spine
4. Abduction — Hip abduction
These exercises could easily be done as a glute workout at home or a glute workout with dumbbells.
For comparison, I kept a fuller leg program with heavy compounds for my glute workout like squats, deadlifts, and bulgarian split squats. to see if it would give me a huge advantage over 90 days.
Butt baselines (Day 1)
- Glute circumference — Tahnee 92cm, me 92.5cm
- Performance — I tested vertical jump and broad jump to see if glute training carries over without practicing jumping
Week 1 was a reality check. I’d been lazy with glute training for the past 6 months, so ramping volume hit hard. Tahnee doubted the plan because she wasn’t getting the same soreness she used to feel after heavy squats/deadlifts. Key point: multiple studies show soreness isn’t a reliable indicator of muscle growth. Bret also chose movements he’s found cause less soreness and muscle damage than squats, deadlifts, or split squats, helping you recover faster and feel less beat up.
Do squats win in saving a flat butt because of hormones? Heavy squats can spike testosterone around 10%–20%, sometimes higher than leg press, but it only lasts about 15–45 minutes before returning to baseline.
Weeks 2–4 are where the real bottlenecks showed up. Tahnee was nervous about pushing harder because she didn’t want to hurt her back again, and old habits popped up (like skipping warm-up sets). Food became the other constraint: she struggled to eat enough because she was scared of gaining fat, and water weight can mess with your head even when you know it’ll pass.
Around this point, Bret’s 2023 squat vs hip thrust study matters: squats grew quads and inner thighs more, but for glute growth, squats and hip thrusts were equal. By Week 3, Tahnee hit 135lb on hip thrusts for 12 reps and said it felt easy — something she hadn’t done in about six years.
Tahnee also had two edges. First, based on Bret’s experience, women tend to recover faster from lower-body training and can handle more glute volume and frequency. Second, about 80% of her training was dedicated purely to glutes, while mine was spread across quads and upper body.
30-day check-in: my glutes were up 1cm, and we were tied. But Tahnee’s tracking showed she was averaging around 1,500 calories/day and having a hard time eating enough protein, which could stall progress. So I started cooking more, and we enjoyed meals together again.
One more point: does being vegan make it harder to build muscle? A study compared vegans and omnivores who both ate the same protein target (0.7g per pound of bodyweight per day). After 12 weeks of lifting, both groups built the same amount of muscle and strength.
Weeks 5–13, volume went up. Tahnee shifted to three leg days and one upper body day. She’d been doing around 20 glute sets/week and making good progress, and for maximum growth Bret sometimes takes clients up to 30–40 glute sets/week. Then the setback: tightness built in her left upper glute, then into her lower back, and we paused for a few days.
After about a week off, her glutes looked and felt flatter. A short break can reduce glycogen, and since glycogen pulls water into the muscle, muscles look less full — like letting air out of a balloon. Most research suggests it takes at least three weeks or more of no training to start losing actual muscle. We dialed training back from 3 sessions/week to 2 sessions/week and kept going.
Final results
- Tahnee hit two plates on hip thrusts for the first time ever
- My vertical jump improved by about 5cm; broad jump improved by 2cm
Big takeaway: there’s no must-do glute exercise. What matters is good form and choosing movements that fit your body. If you’ve been neglecting your glutes, the simplest start is adding 3 hard sets of hip thrusts to your leg days and paying attention to how it carries over to your other exercises and how your glutes look after a few months.
We both have no butts. — That's my wife. She's trained with one of the most jacked personal trainers for 10 years. From the outside, her life looked perfect. But there was one thing stopping her from being truly happy. 5 years ago, she hurt her back badly doing heavy squats. And ever since then, her butt got flat. Sorry. Flatter than she'd like. But she's not alone. I've gone from cake to pancake because I not only sit more than I used to, but I also find glute training extremely uncomfortable. So, I got lazy with it. But strong glutes don't just make your butt look better in clothes. They help you move better, lift stronger, and can even help with back tightness and knee pain. So, for the next 90 days, we're on a mission to build our glutes. She'll build hers with no squats, no deadlifts, and no heavy loading on her spine, whereas I'm free to use whatever I want. And if my injured wife outgrows me, I go vegan for 30 days. — Without crazy heavy weights, without squats, without deadlifts, can she still grow her glutes? — Yeah, this is a piece of cake. I know it sounds impossible to you because you built your glutes with heavy squats and deads. — That's Brett Contras, the man who literally invented the hip thrust and has dedicated his life to studying and growing glutes. — So, first exercise we're going to try is the glute dominant step up. Okay, I want you leaning forward a little more and reach back right there. Tap. Come back up. To build well-rounded glutes, Brett recommends doing four movement patterns. A lower body press, a lower body hinge, a squeeze, and abduction. He's used a simple approach to transform even the flattest of butts. But because of Tonnie sensitive back, we do have to find workarounds for the heavy barbell exercises Brett would normally use. Starting with a lower body press, where most people would simply squat. — This looks like a squat. glute dominant squat, a box squat with mostly vertical shins. So, you're training the glutes as if you were doing a squat. Anyway, so now that we see that body weight was tolerated well, we have a 15lb dumbbell, so about a 7 kg dumbbell. It's a little harder now. — Yeah. — Yes. This is great. What I want is shin mostly vertical, thigh parallel. This creates the most requisite hip extension torque being furthest out. So, she's getting the stretch. She's getting the torque loading. And then this foot maybe a little back right there. — But now we needed a safer hinge movement instead of traditional deadlifts. This is a single leg dumbbell deadlift, which challenges the glutes as much as normal deadlifts, but requires much less weight. But Brett emphasized the key to activating the glutes rather than the hamstrings is to keep that knee slightly bent. — Yes. Come up. Don't even straighten it out. Yep. Oh, that's — Yes. Right there. Just like that. Perfect. — Okay. So, I'm not coming like full stand. — Yep. Exactly. — How's it feel, Bab? — I feel it. — Another one. — I'm so weak. — So far, we're two for two as we moved into our third type of exercise, the squeeze, which in this case happens to be the exercise Brett actually invented, the barbell hip thrust. — All right, so already I'm thinking, all right, feet back a little. You want the knee at around a 90° angle. Crawl up a little higher on this bench right there. Okay. Now, bust out a couple reps. Let me see your natural form. I'm watching to see if she naturally has a tendency to hyper extend the spine. She doesn't. So, you might be okay doing regular hip thrust. What Brett's watching for as she reaches the top of each rep is whether she's overextending her hips and creating pressure in her lower back, which is the most common cause of back pain when performing this exercise. To avoid this, Brett recommends trying the scoop method where you tuck your chin down and move from the chest down, tilting your pelvis upwards by squeezing your glutes. Now, you won't be able to get as high, but that's a point. — Eight. Great form. Good lockouts. Yes. Okay. — And with Tonnie already lifting heavier than she has in years, we just needed one more exercise to round out her training. A hip abduction movement. — I always call this penalty-free volume. You add it in, it doesn't beat you up. adds to the glute hypertrophy stimulus without fatiguing you much. We're going to put these pads right here so that you get more active range of motion. Now you can hold on the handles. Let's see how this feels. Tap. Make sure you come in and tap. — For this exercise, you first target your upper glutes while sitting upright. But if you lean forward at the end of your set, you then switch tension to your lower glutes. So by pairing both sets back to back, you can target multiple areas of your glutes to finish off your workout. General rule of thumb, if you have low back pain, if it feels off, if you feel anything during the movement itself, don't do it. Skip it. — With the trip to Brett being a success, here is the workout plan Ton is going to now be using, training her glutes twice per week and tracking it all in our Built with Science Plus app. As for me, while I will be stealing some of these exercises, I'll still be doing heavy compound exercises like squats and deadlifts. So, we'll be able to see if that gives me a huge advantage or not after the 90 days of training. On day one, Tony's glute circumference comes in at 92 cm, while mine is just slightly
Segment 2 (05:00 - 10:00)
bigger at 92. 5. But while most people think glutes are just about making people turn their heads, your glutes are actually one of the biggest drivers of power, speed, and force production. The most explosive athletes almost always have incredibly powerful glutes. And then there's mine. — Watch out. Watch out. OUT. OKAY. SO, I also want to see if by training my glutes more seriously, it'll lead to any improvement in how high and how far I can jump without actually practicing it, which on day one is coming in at the winner, right? 51. 9. — Oh, okay. — Wow. Look how far I can jump. — And with our baselines recorded, it's time to start training. Whenever I get close to failure, I get really angry and really mean. Ow. I hate this one. — Week one was rough. For the past 6 months, I've honestly just been lazy with my glutes training and so they're struggling to keep up. As for Tonnie, — I'm a little concerned because I've just finished my first few workouts and my glutes aren't really sore and to me soreness means growth and development. So, I don't know what that's about. — But multiple studies have actually shown that soreness is not an indicator of growth, which is actually why Brett chose some of these exercises. He's found that they don't lead to nearly as much soreness or muscle damage as squats, deadlifts, or Bulgarians do, helping Tony recover faster and feel less beat up. However, one proposed advantage of heavy squats is they boost your testosterone levels. Sounds like a serious advantage, right? Well, there is some truth to this. Heavy squats do actually provide a 10 to 20% spike in testosterone. And the boost we see with squats is higher than it is with other leg exercises like leg press. However, this boost only lasts about 15 to 45 minutes after a workout before returning to baseline. So, while it might explain why heavy squats make me feel like an absolute beast, it's not going to provide me with any hormonal advantage over Tawni. But speaking of hormones, I am noticing a big spike in dopamine as it's the first time in years that Tonnie and I have trained together. Although she says all my enthusiasm can be a bit much. — You don't want a hug? — No. Get away from me. — Which makes it difficult when I offer coaching or push her to train harder. — Implementing my last set where I did 13 reps and I would say I did max effort. Like that was my max. — I have to tread very carefully. We could put it as max. You did push hard that — I did. So I pushed to my max. But so far, things weren't going quite as smoothly as we expected. Despite doing every exercise correctly, Tonyie was very scared of pushing harder, just in the fear of hurting her back. Again, — my left leg, like my glute, it feels like it's cramping, but also my left side is where I have an issue with my SI and parapformis. So, it's hard for me to decipher if I'm having a glute cramp or if I've slightly hurt myself. And on top of that, she was struggling to eat enough. Not because she wasn't hungry, but because she was scared of gaining fat. — If I'm laying it all out on the table here, I'm on my period. Whenever I'm on my period, I always gain a few pounds. Usually like 2 to 3 lb. Like I can see the water weight. It sits in my stomach. It sits like heavier in my face. So, the thought of having to put weight on isn't a pleasant thought for me. As for me, my glutes were finally getting used to the new volume and actually started boosting my squats, making them feel smoother and much stronger. So, today I got squats on the menu. And one thing that I'm actually doing is just a very subtle tweak with my form to emphasize the glutes a little bit more. And you guys can try this, too. One way of performing the squat is a bit more quad dominant. And so, your back is upright and you let the knees drive forward. But what I'm doing is since I want to focus on the glutes a little bit more, I'm actually going to focus on keeping my shins more vertical and pushing my hips back, leaning forward a little bit. All it does is it shifts the emphasis a little bit from the quads, more so to the glutes. And hopefully that gives me a little bit more of an edge to help win this challenge. And while you might be thinking squats are giving me a huge advantage over Tawni, back in 2023, Brett actually ran a study comparing squats against hip thrust. And while squats did grow the quads and inner thighs more, for glutes growth, they were both equal. And based on Tony's progress so far, it honestly seems like I'm the one that was starting to lag behind. — I'm telling you, the glutes are popping. Holy. — I don't see it, so I don't know. — What do you mean you don't see it? The camera definitely sees it. Look at this. — By week three, Tonnie was sending mad PRs, and the gains were clearly coming in. — Bab, you just did 135 lbs. That's a plate. You said — I know. I'm really proud to be honest
Segment 3 (10:00 - 15:00)
cuz I haven't done this weight in like 6 years. My girls are proud of me too. And it actually felt really easy. Like that was 12 reps. — However, Tonnie is not the only one getting the cake. — Week three. Wo wo. Dennis, you see that? — Wow. If this is week three, can you imagine what week 10 is going to be like? Go. I recently watched Heated Rivalry where the actor's glutes blew up online, showing the world just how much ladies appreciate a strong butt. — How important would you say glutes are on a guy? — I like athletic glutes on a guy. I don't want like a big booty, but I want you to have like — glutes. Yeah. — Okay. — Like we don't want a guy that can just do like bicep curls and go do a squat. — Now, technically, Tony actually has two big advantages over me. First, based on Brett's experience, he's noticed that women seem to recover faster from lower body workouts than men do and can train their glutes with more volume and frequency. And while the heavy weights I'm using may be a factor, I am noticing that by the time Tonnie is ready to go for her next workout, I still need another day or two to recover, and I just can't keep up with how many sets she's been doing. But second, and this is the biggest factor, about 80% of Tony's training right now is dedicated purely to glutes. Meanwhile, I'm still doing a lot of volume for my quads and my upper body. And although this has yet to be actually studied, when I wanted to grow my shoulders in the past, I scaled back everything else and poured more volume into my shoulders, and it led to the fastest growth I've ever seen. Because when your body has fewer competing priorities, it can move more resources towards one area. So, if that same principle applies here, Tonnie should be able to outgrow my glutes, which is concerning because I love my meat. And if she wins, I'm going vegan for 30 days. Let's see what measuring tape says. 30 days, your booty is up exactly 1 cm. — Oh, — was that good? — That's very good. — And now it's my turn to measure my glutes after 30 days. The result was not what I was expecting. Come on. What are we at? — 93. 5. — No way. Okay. My glutes have also grown 1 cm. We are tied. But I may start out growing her because based on her tracking in our Bit Science Plus app, she wasn't reaching her target calorie intake. If that continued, her progress might eventually stall. So to motivate her, I decided to do something I honestly hadn't done for her in years. I cooked for her. We'll see what she thinks in just a sec. But Tanya and I actually met about 10 years ago at the gym. But as my work got busier and with her back injury, we started spending less and less time together. So, my hope is this experiment gives us more to do together and rebuild more than just our bodies. Hopefully, I didn't ruin all my chances by butchering this food. — Oh my god. You actually like it? — Mhm. — Oh, — it's really good. — Like a restaurant. — Really? — Mhm. I'm so happy. — It's the first time in a while that we actually sat down at home and enjoyed a meal together. Now, some of you might be thinking Tonyie has a huge disadvantage with her diet, that you need to live off chicken breast to build muscle. And I used to think that, too. But the latest research is making me rethink that. A new study took two groups of lifters, vegans and meat eaters, and had them both eat 0. 7 g of protein per body weight per day. Now, the vegans ate a variety of protein sources like tofu, soy, and lentils. Whereas the meat eaters obviously relied on meat, protein shakes, and eggs. Now, you'd expect the meateers to have at least a small advantage, but after 12 weeks, both groups ended up building the same amount of muscle and strength. So, as long as you're getting enough protein, it doesn't seem to matter too much where that protein is coming from, which honestly makes me slightly less terrified of going vegan for 30 days. But, I still really do not want to give up my favorite foods. And even though we're only 30 days in, I do want to see if we can pass the bar test. I can't even feel it. — Your back stopped it. — Unfortunately, we both couldn't stop the bar. But if you watch closely, I kind of did manage to stop it a little bit. And that is when Tonnie decided to take her glute training to the next level. So far, Tony's been doing around 20 sets of glutes per week and seeing some pretty good progress. Holy. Wow, that's crazy. — But for Brett's clients that wants the most growth possible, he takes this all the way up to 30 to 40 sets per week. That extra volume seems to speed up their growth. And so for Tony, this spends ramping up her glute training from two to 3 days per week. — And that makes me really nervous because I'm not going to lie, with my back injury. So it's just like a fear thing for me. And I really hope that I don't hurt myself, hurt my back because
Segment 4 (15:00 - 20:00)
I really want to reach my glute goals. I don't want to let Jeremy down. like get frustrated and let myself down. — Now, at first everything felt fine, but slowly tightness started building up in her upper left glute and then into her lower back and eventually this happened. And so we decided to put the challenge on pause for a few days. H. So, I hurt my back at the gym yesterday and I came today to try to work out and it's very clear that I'm going to need a few days off, which is really frustrating for me. — Connie is at work right now, but she just sent me a text and uh just saying how she's not feeling too well. She's a bit sad and I think what's going on is that this challenge is putting a lot of pressure on her. I think like she not only wants to win obviously, but she just doesn't want to let you guys down. After a few days of rest, thankfully her back started feeling better. — I feel so good. — Do you want to go back on the challenge? Totally fine if you want to drop out. No hard feelings. — Are you scared you're going to lose? — No, I'm trying to be nice. Okay, but fine. I'll take that as a sign as you are ready to go back and I'm just going to say I'm not going easy on you. Okay. — All right. — I want you spicy, too. — All right. Let's go. But after just a week off of training, Tony's glutes felt and looked a bit flatter than usual. And she started worrying she was losing muscle. And she wasn't just imagining it. When you stop training for a week or two, your muscles store less glycogen. And since glycogen pulls water into your muscles, they'll look less full. It's kind of like letting air out of a balloon. But while your muscles might look flatter and your strength might also dip because you just haven't practiced your exercises, most research suggests it takes at least 3 weeks or more of no training to start losing actual muscle. That said, we definitely do not want her to hurt her back again. So, even though we might see a bit more growth training her glutes three times a week, it was a no-brainer to dial her training back to just two. And to help keep her consistent, we even found some creative ways to do her workouts at home, which we've even added to our Bit with Science Plus app. That way, our members don't need to always rely on the gym to make progress. And with only a few weeks left, Tony's glutes were making the fastest progress ever. And if I'm going to be honest, even if I lose and have to go vegan, this challenge really is a win-win for me. While Tony's glutes were blowing up, all of my glute training was actually leading to some unexpected benefits. today. That felt more like a jog. My treadmill can't even go any faster, but definitely feels like my glutes are contributing more to the run. Like, it's helping me with my run. And all these benefits weren't from actually changing much to my leg workouts. I mainly just started doing hip thrust again and experimented with some of Brett's exercises, which helped my other exercises feel stronger, and more importantly, just help my body move and feel a lot better than it used to. So, if you've been neglecting your glutes like I was, just start by adding three hard sets of hip thrust to your leg days. But with one week before our final results, we decided to take a trip to Hawaii to show off our glucans. Holy moly. What the heck do we have here? And on the final day of the experiment, she didn't just bring the heat to the beach. She broke another PR. First time ever, two plates on the hip thrust. — I am finally done my glute video with Jeremy. I am so grateful that Brett Ferris let us come into his home. He showed me a bunch of lower back friendly glute exercises and I'm forever grateful for him for that because doing this challenge just showed me that I am capable and there are ways of getting a booty. As for me, I've got one more final test. After 90 days, did these glute gains actually improve my jump performance? So, that is pretty much a 5 cm increase, which is pretty impressive. I wasn't sure if my glute strength growth would impact vertical jump at all. But that honestly motivates me even more than just the growth is seeing the athletic performance there cuz I love playing sports too. So my vertical jump went from just beating average to now being on the high end of above average. Though still not enough for my Asian mom to be proud, but broad jump scored excellent on day one and I still managed to increase it by 2 cm. — Not bad. But now it's time to measure the glutes and see who actually grew them the most in the past 90 days. Final day is here. I am extremely nervous, especially after seeing what I'm up against today. I'm done. There's no way. So, you started at 92 cm and today you are at 94 cm. 2 cm of growth. Good job, Evie. Good I won a 95 now. Did I win? — Please, God. There's no way. — That's where you are. — Yeah. — There's no way. — You can't. — All right. Do it again. — You can't eat them.
Segment 5 (20:00 - 21:00)
— You're right here. All right, guys. We have measured and I am what? — Plus two, — which means — I am plus 1. 5. — Which means I'm cooked. You won. You won. I also won. But it wasn't until I tried on my wife's shorts that I truly appreciated my new glute gains. So, while this does mean I have to go meatless for 30 days, at least this gives Tonnie and I a chance to enjoy more dinners together. Oh, and she's got some serious cake that I could stare at all day. So, still feels like a win for me. I'm honestly just so proud of Tonnie. She's overcome like some of her biggest fears and she's genuinely enjoying the gym again. and she did all of this without lifting crazy heavy. I think it goes to show you that there's no musdo exercises. What matters the most is good form and choosing exercises that actually fit your body and feel good. And that is actually why we created the Build with Science Plus app. Both mine and Tony's workouts are in there, but the program adjusts based on how your specific body responds to your plan. So, you're not just copying somebody else. And if you want to try it, you can test it out completely free for 2 weeks. Just scan the QR code here or head to builtwithwithscience. com. And if you guys want to simplify your glute training and focus on the only two exercises you actually need to fix your flat butt, give this video a watch next, which we recorded with Brett. Thank you so much for watching.
