Here's the short version. The trials behind tesamorelin, sold as Egrifta, set one checkpoint: 26 weeks. That's when deep belly fat was measured and compared with placebo [1]. Those pivotal results do not establish a week-by-week response timetable.
| Time point | Study | Who | People | Result | Note |
|---|---|---|---|---|---|
| 20 weeks | Baker 2012 [4] | Adults 55 to 87, 66 with mild cognitive impairment | 152 | Memory and thinking composite favored the drug (P=.03); IGF-1 +117%; fasting insulin +35% in the impairment group | Off-label, one trial |
| 26 weeks | Falutz 2007 [1] | Adults with HIV and extra abdominal fat | 412 | Deep belly fat −15.2% vs +5.0%; triglycerides −50 vs +9 mg/dL | The main approval trial |
| 26 weeks | Falutz 2010, pooled [2] | Adults with HIV on antiretroviral therapy | 806 | Deep belly fat treatment effect −15.4%; fat under the skin unchanged | Both phase 3 trials combined |
| 52 weeks, stayed on | Falutz 2010 extension [2] | People re-randomized to keep taking it | 246 | Deep belly fat −17.5% from the original baseline | Loss held, didn't grow much |
| 52 weeks, stopped | Egrifta label, extension [7] | People switched to placebo at week 26 | 135 | Deep belly fat +22% and +16% from week 26, vs 0% and −5% for those who stayed on | The effect faded off the drug |
| 12 months | Stanley 2019 [3] | Adults with HIV and liver fat of 5% or more | 61 | Liver fat −4.1 points vs placebo (−37% relative) | Off-label, one trial |
Every result is versus placebo unless marked as change from baseline.
The 26-week result is the main checkpoint in the trials
FDA's approval rests on two 26-week trials, where tesamorelin reduced deep belly fat by about 15% compared with placebo. In the first, 412 adults with HIV took the drug or placebo for six months. Deep belly fat fell 15.2% on tesamorelin and rose 5% on placebo [1].
Pooling both phase 3 trials, 806 people in all, gave a treatment effect of −15.4% at 26 weeks [2]. Fat under the skin barely moved. That's the point of the drug: it targets the deep fat around the organs, not the fat you can pinch.
Triglycerides, a blood fat, dropped in the same window. They fell 50 mg/dL on tesamorelin and rose 9 mg/dL on placebo [1]. Body weight didn't budge in either trial [7].
IGF-1 rises on treatment, and that's the number your prescriber tracks
IGF-1, the hormone growth hormone drives, rose 81% on tesamorelin versus a 5% fall on placebo at 26 weeks in the main trial [1]. The label also reports above-normal IGF-1 as early as 13 weeks. Neither observation supplies a reliable week-by-week personal response timetable.
Your prescriber watches IGF-1 for a different reason: safety. The label says the effects of long-term high IGF-1 are unknown and asks for it to be checked during treatment [6]. Ask what level they're aiming for and when they'll re-check it.
At one year the loss held for people who stayed on it, and came back for people who stopped
People who stayed on tesamorelin kept the reduction: deep belly fat was 17.5% below baseline at 52 weeks [2]. That's only a little more than at 26 weeks, so most of the change had already happened by six months.
The trials also tested stopping. At week 26, people on the drug were randomly switched either to more tesamorelin or to placebo. The label reports what happened over the next 26 weeks [7].
In plain terms, the fat came back within six months of stopping. The trial benefit depended on continued treatment. If you're weighing whether to start, factor in that fat may return after treatment stops, and what that costs is in our tesamorelin cost guide.
Other off-label endpoints used different checkpoints
Two trials outside the approved use measured other outcomes, on longer or shorter clocks. Neither is part of the label.
- Liver fat, 12 months: in 61 adults with HIV and fatty liver, liver fat fell 4.1 percentage points more than on placebo, a 37% relative drop. By the end, 35% on the drug and 4% on placebo had liver fat under 5% [3].
- Memory and thinking, 20 weeks: in 152 adults aged 55 to 87, a composite score favored tesamorelin (P=.03). IGF-1 rose 117%, and fasting insulin rose 35% in people with mild cognitive impairment [4].
Each is one trial. These findings do not change what the drug is approved for.
The label says Egrifta isn't a weight-loss drug
If you were hoping to see the scale move, the label is direct about it.
EGRIFTA WR is not indicated for weight loss management as it has a weight neutral effect.[7]
The label also says long-term heart safety hasn't been established. And it tells prescribers to weigh whether to continue in people whose deep belly fat hasn't dropped [6]. That's the label's own answer to "why am I not seeing results": not everyone responds, and imaging is how you find out.
One reanalysis defined a responder as someone whose deep belly fat fell at least 8% [5]. Muscle results from that same analysis are covered in does tesamorelin build muscle.
Four questions to ask your prescriber about timing
- When will you re-check my deep belly fat, and how: a scan or waist measurements?
- What IGF-1 level are you aiming for, and when is the first blood test?
- If my belly fat hasn't dropped by six months, do we stop?
- If I stop later, what should I expect, given the fat returned in the trials?
The pivotal fat-loss timelines describe adults with HIV
The timelines describe adults with HIV-associated abdominal fat. These pivotal HIV trials do not establish a response timetable for healthy adults seeking general fat loss, energy or anti-aging effects. The cognition trial also measured body composition, including a 3.7% DXA lean-tissue increase, but did not establish a general weight-loss indication.
For ordinary prescription care, the approved products are brand Egrifta formulations, as our page on getting tesamorelin legally explains. The cited evidence does not establish a benefit from combining it with another growth-hormone peptide; see tesamorelin and ipamorelin together.
If your real goal is belly fat or weight, start with our metabolic shortlist. If you're comparing growth-hormone options, how long sermorelin takes to work sets out a very different evidence record.