Q&A log
Semaglutide FAQ
Direct answers, cited to the record. No throat-clearing.
How much muscle do you lose on semaglutide?
There is no single number. A body-composition substudy that scanned tissue with DXA found the weight lost with semaglutide 2.4 mg includes both fat and a meaningful proportion of lean (muscle) mass [13]. The amount varies, it tracks with how fast and how much weight is lost, and the lean-mass finding is what drives research into protein and resistance training.
Can semaglutide reduce alcohol cravings?
Early evidence points that way. In a phase-2 randomized trial (n=48) in adults with alcohol use disorder, low-dose semaglutide reduced laboratory alcohol self-administration (beta -0.48, P=0.01) and predicted greater reductions in heavy drinking [8]. Rodent work traces the effect to reward circuitry [9]. It is promising but early — not an approved use.
Does semaglutide cause facial aging or loss of facial volume?
Not directly. People report a thinner, more hollow face during treatment, but it is widely attributed to rapid weight loss — losing facial fat — rather than to the drug itself. The related hair shedding is linked to the rate and magnitude of weight loss too (telogen effluvium), and is usually described as temporary [15].
How can you preserve lean muscle while losing weight on semaglutide?
Research into the lean-mass loss seen on semaglutide points toward adequate protein intake and resistance training as the levers worth studying to protect muscle during weight loss [13]. This site logs that research direction; it does not set protein targets or training plans. Specific decisions belong with a qualified clinician.
What is semaglutide?
Semaglutide is an FDA-approved GLP-1 receptor agonist — a lab-built copy of the gut hormone GLP-1, re-engineered to last about a week per dose [12]. It is used for type 2 diabetes, chronic weight management, lowering major cardiovascular events, and (2025) the fatty-liver disease MASH, as a once-weekly injection or once-daily tablet [11].
What is semaglutide used for?
It is FDA-approved for type 2 diabetes, chronic weight management, reducing major adverse cardiovascular events in people with established cardiovascular disease and overweight/obesity, and (2025) metabolic dysfunction-associated steatohepatitis (MASH) [11]. In STEP 1 it produced a mean -14.9% body-weight change at 68 weeks [1].
How does semaglutide work?
It activates the GLP-1 receptor, which prompts glucose-dependent insulin release, suppresses glucagon, and slows gastric emptying [12]. Its weight effect is mostly central: it reaches brain appetite circuits — the arcuate nucleus and area postrema — activating satiety neurons and quieting hunger neurons, reducing food intake without lowering energy expenditure [4].
How does semaglutide work for weight loss?
Mainly through the brain. Semaglutide reaches hypothalamic and brainstem appetite centers, where it activates POMC/CART satiety neurons and inhibits NPY/AgRP hunger neurons, cutting food intake and shifting food preference without reducing energy expenditure [4]. Slowed gastric emptying adds to the sense of fullness [12]. In STEP 1, the result was a mean -14.9% body-weight change [1].
What is the semaglutide dosage for weight loss?
The dose studied for weight management is 2.4 mg once weekly, reached by stepping up from 0.25 mg over about 16-17 weeks to limit nausea [16]. That 2.4 mg dose produced a mean -14.9% body-weight change at 68 weeks in STEP 1 [1]. These are label- and trial-documented figures, not a recommendation.
How many mg is 40 units of semaglutide?
"Units" on a U-100 insulin-style syringe do not map cleanly to milligrams of semaglutide, because semaglutide is dosed in milligrams, not insulin units, and concentrations vary by product. Converting units to mg by eye is a known source of dosing error — one reason approved pens are pre-set in mg [12]. This site does not provide dose conversions.
What is compounded semaglutide?
Compounded semaglutide is made by a compounding pharmacy rather than the approved manufactured product. It was permitted during a federally declared shortage (roughly 2022 to early 2025) and curtailed once the shortage resolved [11]. It falls outside the approved-product evidence base, and documented concerns included dosing errors and products with unverified ingredients [5].
What are the side effects of semaglutide?
Gastrointestinal effects dominate — nausea (about one-third of patients), vomiting, diarrhea, and constipation — mostly mild-to-moderate, transient, and concentrated around dose increases [5][16]. Cited cautions include a thyroid boxed warning, pancreatitis and gallbladder warnings, retinopathy in rapid glucose correction, and lean-mass loss [2][5][13]. The full list is on the effects page.
How long does it take for semaglutide to work?
Blood-sugar and appetite effects begin within the first weeks, but the dose is deliberately raised slowly over about four months to reach the maintenance level [16]. Weight-loss trials measure the full effect over 68 weeks, where STEP 1 recorded a mean -14.9% change [1]. Reported appetite suppression often shows up in the first week or two, though that is anecdotal.
How long does semaglutide stay in your system?
A long time. Semaglutide's elimination half-life is about one week, with effectively complete clearance roughly five weeks after the last dose [12]. The long tail comes from tight, reversible albumin binding plus resistance to the DPP-4 enzyme [12], and it is why label guidance advises stopping well before a planned pregnancy [11].
What is the half-life of semaglutide?
Approximately one week — commonly cited as ~165-168 hours — for both the injection and the oral tablet [12]. Two structural features drive it: a C18 fatty-acid side chain that binds albumin reversibly, and a position-8 substitution that resists DPP-4 degradation [12]. Effectively complete clearance takes about five weeks [12].
Is oral semaglutide as effective as the injection?
They are different deliveries of the same molecule. The oral tablet's bioavailability is low (~0.4-1%) even with the SNAC absorption enhancer, so it must be taken fasted with minimal water to work [21]. Higher oral doses (25-50 mg daily) were studied in obesity programs; the once-weekly injection is the form used in the large STEP, SELECT, and FLOW trials [1][3][6].
How long does it take for semaglutide to suppress appetite?
Mechanistically the appetite pathways are engaged from the first doses — semaglutide acts on hypothalamic and brainstem circuits that control hunger and satiety [4]. People commonly report quieter "food noise" within the first week or two, though that is anecdotal. The dose is still escalated slowly over months to reach the full maintenance level [16].
Why am I not losing weight on semaglutide?
Response varies between people, and trials report a range around the average; STEP 1's -14.9% is a mean, not a guarantee [1]. The dose is also raised gradually over about four months, so early weeks are sub-maintenance [16]. This is general context from the record, not personal medical advice — individual reasons are a clinician's question.
Does semaglutide make you tired?
Fatigue is commonly reported, especially in the day or two after an injection and during the early weeks, often easing with time. It is frequently linked to eating very little or under-hydrating while appetite is suppressed. These are real-world reports; the dominant clinically documented effects are gastrointestinal [5].
Is semaglutide a GLP-1?
Yes — semaglutide is a GLP-1 receptor agonist, a synthetic analogue of the natural incretin hormone glucagon-like peptide-1 [12]. It shares about 94% of its sequence with human GLP-1, with two engineered changes that extend its action from minutes to about a week [12].
Does semaglutide cause hair loss?
There is a reporting signal. A pharmacovigilance analysis flagged alopecia with semaglutide and tirzepatide [14], and a dermatology study linked telogen effluvium — reversible diffuse shedding — to the magnitude and rate of weight loss [15]. The signal is most consistent with rapid-weight-loss shedding rather than a direct drug effect, and is usually described as temporary.
How fast does semaglutide work?
Glycemic and appetite effects start within the first weeks, but the dose is escalated slowly over about four months to its maintenance level [16]. The full weight effect is measured over the long trials — a mean -14.9% body-weight change at 68 weeks in STEP 1 [1]. Anecdotally, many report appetite changes within the first week or two.