CommunitySide Effects

Fatigue?

31 replies30 peopleJun 3, 2026☆ Follow
Summary

Does retatrutide cause fatigue and how long does it last?

Many users report initial fatigue that is often strongest in the first weeks or right after a dose increase and tends to ease as the body adapts. Several link it to rapid drops in calories, low protein or carbs, dehydration, or poor sleep rather than the drug alone. A minority feel no fatigue or even more energy, and a few note it persists at higher doses or feels more like lack of motivation or anhedonia.

What this discussion establishesWhere people disagree

Whether fatigue is mainly from the medication itself or from the calorie deficit and lifestyle changes that accompany it

Still open

How much individual factors like starting weight, sex, or concurrent peptides truly determine who gets tired

Nothing here is advice.

31 replies · 30 people
WarmTimber31archiveopening postJun 3

Has anyone else been dealing with tiredness while taking Reta? I'm considering starting but want to know how bad the fatigue usually gets. Mounjaro left me pretty wiped out before.

ClearBeacon24archiveJun 3
↳ replying to @WarmTimber31 (opening post)

I've mostly noticed it in women for some reason, usually a day or two after the shot.

IronLantern24archiveJun 3

It hit me hard the first two months, sometimes feeling like narcolepsy. Once my body adjusted it mostly went away. Now it only shows up if I skimp on protein.

GreenSignal63archiveJun 3

On a low dose I actually feel more energetic, especially during workouts. My partner started and has more fatigue, though that might be the kids more than the medication.

BlueWillow27archiveJun 3

For me it's mostly low motivation even though I can still sleep. When it hits, work and training both suffer.

SlowThistle29archiveJun 3

Yes, I raised the dose too fast and felt quite tired the first week. Dropping back down made the fatigue much milder.

LevelMarble91archiveJun 3

No fatigue for me or my wife. We both began at 2 mg and are now at 5 mg twice a week. We've also used SS-31, MOTS-C, and NAD+ a few times weekly.

ClearQuill84archiveJun 3
↳ replying to @WarmTimber31 (opening post)

I'm actually feeling good energy on Reta right now. Adding Semax a week ago seemed to lift it further. It probably depends on the person. I'm only slightly overweight, which might be why my response is positive.

PlainAlder11archiveJun 3

Not really. I'm tired by the end of the day and sleep isn't great, but I manage. Some days are better. I get up around 5 and go to bed around 8. It was worse a month ago until I started using Liquid IV in two Gatorade bottles, one a day. That helped, though I watch the sodium and only use half a packet.

CopperMarble58archiveJun 3
↳ replying to @BlueWillow27

I started at 2 mg and am at 4 mg now. The lack of motivation is real. I still get my steps in but tend to put off the gym a lot.

AmberKettle85archiveJun 3

I had some fatigue at the start, but then realized I was barely eating or drinking when work got busy. Once I increased calories and paid attention to water, energy improved and sleep got better too. Tiredness seems tied to the deficit, but the same deficit feels easier on Reta than off it.

BlueKettle52archiveJun 3

Started eight weeks ago. Some fatigue showed up in weeks three and four the day after pinning, but it wasn't major. Now the only tiredness comes from the calorie deficit, and I've found that keeping carbs up helps prevent it.

BrightMeadow31archiveJun 4

I felt it the first few weeks. Magnesium helped me get deeper sleep. Staying well hydrated also cut down nausea and headaches, and I use electrolytes during workouts.

KeenPebble33archiveJun 4

It happened to me early on. Makes sense after suddenly cutting food so much. It lasted a few months while weight was dropping fast but eventually faded. It goes away if you stick with it and keep protein intake up.

BrightSignal26archiveJun 4

First week on Reta and fatigue hit hard. The change was obvious. I can barely lift what I normally do at the gym. It doesn't bother me much but I feel physically drained.

QuietCinder90archiveJun 4
↳ replying to @WarmTimber31 (opening post)

Yep, completely exhausted on just the starting dose with no energy. Weight is coming off and hunger is low. How are you handling your fatigue right now? Have you tried any vitamins?

GreenQuill54archiveJun 4

I get very tired between 12 and 24 hours after a dose, along with brain fog. It passes fairly quickly but has been consistent so far.

SlowMarble44archiveJun 4

Hard to tell since I'm always tired anyway, before and after Reta. If it hurts sleep then that would explain feeling more fatigued.

SharpHarbour71archiveJun 4

Completely true in my case too since every GLP triggered awful exhaustion plus zero ability to feel any pleasure. Everything seems far more normal after moving to that single milligram weekly upkeep amount. Only after the switch did I grasp how much they had been weighing me down.

IronKettle44archiveJun 4
↳ replying to @ClearBeacon24

My sister mentioned the same about fatigue. I also saw resting heart rate go up and HRV drop, so I removed it from my stack. Thanks!

WryLedger77archiveJun 4

I get fatigue and nausea for one or two days after the shot, worse when raising the dose. I moved my shot day so heavier workouts fall further away from it.

NorthQuill17archiveJun 4

Definitely very tired, especially a couple days after shot day. I'm on 2.5 mg weekly and my husband on 4 mg sees the same. I use NAD+ for quick energy and Epitalon for sleep. Need enough food with protein and carbs. Also check if it's actual fatigue or anhedonia, which is another common side effect. I wasn't full of energy before starting anyway.

BlueCinder18archiveJun 10

Would like tips on fighting fatigue. On 4 mg a week it hits within the first 24 hours after pinning. Probably because appetite is suppressed and I'm not eating enough calories.

RustBramble70archiveJun 12

This thread is useful. I've been microdosing 2.5 mg every four days since March, added 1 mg Tesa daily a couple weeks ago and Glow five times a week. Lost 30 lb in three months while training three times a week and had great energy until about a week ago when both energy and motivation dropped. Now I drag and feel brain fog plus constipation. Libido is fine so probably not anhedonia. Advice here points to calorie deficit or hydration, so I'll focus on those and maybe add carbs and fiber. Any other ideas from the group, including peptides? I was enjoying the high energy and want it back.

KeenFenwick72archiveJun 12
↳ replying to @WarmTimber31 (opening post)

I don't get it. I started at 0.5 mg. Couldn't sleep the first and second night though.

KeenFenwick72archiveJun 12
↳ replying to @RustBramble70

I tried adding roughage along with mineral salts to what I was taking. They seemed to offer some relief without causing any trouble.

PatientAlder45archiveJun 12
↳ replying to @WarmTimber31 (opening post)

Yes, 23F. I've had two doses, 0.5 and 1 mg each week. Didn't realize this was common until seeing the thread. Not sure if it's extreme but even espresso didn't help, still had brain fog and wanted to rest. Second shot was last Saturday and today (Friday) I finally have more energy. At least sleep and no constipation are fine, small wins.

RustPebble66archiveJun 12
↳ replying to @KeenFenwick72

I'm on 0.5 mg, first shot Monday, planning to go up 0.5 mg each week if all goes well. Also had trouble sleeping the first night. Took longer to fall back asleep after waking twice, which is unusual for me.

GreyCompass27archiveJun 12

Can't figure Reta out overall. Luckily I've been able to sleep in a bit, which offsets trouble falling asleep. Before increasing the dose I had great energy and motivation. Only at 4 mg a week and now very unmotivated in the morning. Skipping a run or gym leaves me in a funk all day. Calorie deficit probably plays a role but it's frustrating. Still don't regret it, just wish I felt as good as I look.

QuietSignal61archiveJun 12

Tiredness shows up now and then. I keep up with my supplements, have four meals each day, and move around whenever time allows.

PatientSignal25archiveJun 12
↳ replying to @RustBramble70

Same thing happened to me until I added SS-31 and MOTS-c daily at 20 units each, then the fatigue went away.

PlainAlder11archiveJun 14
↳ replying to @QuietSignal61

Electrolytes help too. You should probably be getting them while on Reta anyway.

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Fatigue? · ZyraTrack Community