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Varying calorie intake

8 replies7 peopleApr 26, 2026☆ Follow
Summary

Does adding weekly 24-36 hour fasting days while on retatrutide preserve muscle better than a steady daily calorie deficit?

Participants note that Reta makes longer fasts easier but agree strength training plus adequate protein is the main way to limit lean mass loss. Some cite research suggesting alternate-day fasting may spare muscle compared with daily restriction, while others point out that very low intake on non-fasting days still risks under-eating and glycogen depletion. Early side effects like reduced workout performance are often blamed on lower carbs rather than actual muscle loss. Overall the group favors spreading protein, adding workout carbs, and avoiding extreme weekly fasting.

What this discussion establishesWhere people disagree

Whether fasting days truly reduce muscle loss more than consistent moderate deficits, and how often fasting can be done without losing training performance.

Still open

Actual muscle loss rates on Reta with or without fasting, and long-term sustainability of the approach.

Nothing here is advice.

8 replies · 7 people
SteadyCinder74archiveopening postApr 26

Has anyone kept doing a fasting day once they started Reta? Any sign that a 24- or 36-hour fast once a week, then eating normally the other days, helps hold on to muscle? That would mean the deficit only happens on one or two days and the rest of the week stays at maintenance. I already like intermittent fasting and Reta makes longer fasts feel much simpler. Do the usual benefits still show up? It is surprising how much work it can take to hit enough calories on the regular days.

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PlainQuill53archiveApr 26

A big calorie drop will cost both fat and lean tissue no matter what. The main way to keep more of the lean mass is regular strength work, which tilts the loss toward fat even though some lean tissue still goes. Plenty of people have talked about trying to add size on Reta thanks to how it handles nutrients, and that might fit with the idea of eating freely on some days and cycling carbs. I will keep an eye on this thread to see what more experienced users think.

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IronWillow59archiveApr 26

There is a lot of poor information out there, so it is tough to sort out. Looking deeper into the research, several papers suggest fasting may hold muscle better than everyday dieting. One review compared alternate-day restriction with daily restriction for weight loss, and another looked at intermittent versus daily calorie cuts. Some work also tracked longer-term fasting effects.

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SteadyCinder74archiveApr 26
↳ replying to @IronWillow59

Appreciate the papers. I have only been on a low dose of Reta for two weeks and the scale is moving quicker than I wanted. Even though I lift hard three times a week I think some muscle may be coming off. Before Reta I was adding weight or reps steadily after getting back to training following an injury layoff, but the last two weeks have been flat and the sessions feel tougher with longer rests needed. I realize I should track protein more carefully and choose better sources. I just bought some whey and taurine because it is supposed to help with recovery. Open to other ideas. Losing muscle would set back my rehab from the injury.

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ClearLantern81archiveApr 26
↳ replying to @SteadyCinder74

I understand the concern. What you describe happens often when people first start Reta, especially if training was already consistent. At only two weeks it is probably not real muscle loss yet, more likely the result of fewer calories, fewer carbs, and lower muscle glycogen. That alone can make lifts feel heavier without any meaningful tissue loss. Focusing on protein is the right move and spreading it across meals helps. Adding whey is useful on days when hunger is low. Putting some carbs around training sessions can also ease the strength and recovery drop. When carbs stay too low the weights feel heavier and rests stretch out. It is also wise not to let calories fall too far because these drugs make it easy to undereat without noticing.

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PatientTimber45archiveApr 26

Are you getting weaker between workouts? If strength is dropping you are probably losing muscle. I went almost two weeks without eating much on Reta because of stomach problems and lost about five percent of my strength even though I was on TRT.

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SteadyCinder74archiveApr 26
↳ replying to @PatientTimber45

Strength felt off especially last Friday when I had to stop a circuit midway for a long rest. It could also be low carbs and empty glycogen as someone else mentioned. I am back on TRT at a normal dose now. I paused it after surgery because some studies linked it to tendon issues, but I was talked out of that and told the studies were weak and stopping was a bad idea while recovering. Anyway I am trying harder to log protein and calories and eat even when I do not feel like it. This peptide is stronger than I expected at just 1 mg and it is my first GLP-1 so the effects hit me hard.

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RustCompass19archiveApr 26

I cannot fast on Reta at all. I wake up at night needing a snack because blood sugar drops too low, something that never happened on Tirz. To the original question, fasting one day and staying at maintenance the other six probably will not create enough of a deficit and is unlikely to be sustainable. Two zero-calorie days would be closer to what is needed since activity is low on fast days. It is better to eat more on lifting days to keep strength up and protect muscle, while still getting protein on rest days. Strategic fasting can work but doing it every week feels excessive. Extra carbs also help when rest times are getting longer, and that is usually a fuel or electrolyte issue rather than true strength loss. Do you get lightheaded on moves that raise heart rate like squats?

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CopperAlder25archiveApr 26

It matters where you start. If body fat is already under 15 percent I would skip that fasting plan and also avoid very low-carb eating. Training, enough protein, carbs timed around workouts, and maybe extra meals are the better route.

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Varying calorie intake · ZyraTrack Community