NAD+ is mostly offered as a longevity treatment, and a common follow-up question is whether it also helps with weight, which is something human trials can actually answer.
The short answer from human trials is that it has barely been tested for weight, and where related compounds were tested the effect was small or absent. The broader evidence on injections is in NAD injections: benefits and evidence.
Where the idea comes from
NAD+ is a coenzyme involved in how cells turn food into energy, and the rationale for giving more of it starts in rodents. A 2021 trial paper summarizes that work: in rodents, obesity and aging impair NAD+ production, which contributes to metabolic dysfunction [1].
The reasoning is that restoring NAD+ might reverse some of that dysfunction. It is a plausible mechanism, but it was built from animal models, and the human trials below are the test of whether it carries over.
Most human studies do not give NAD+ itself. They give precursors, nicotinamide riboside (NR) or nicotinamide mononucleotide (NMN), which the body converts into NAD+. The difference is explained in NMN vs NAD.
What the trials in overweight and obese adults found
| Trial | Who | What and how long | Weight or body composition |
|---|---|---|---|
| Dollerup 2018 | 40 men with obesity, aged 40 to 70 | NR 2,000 mg a day, 12 weeks | No effect on body composition |
| Remie 2020 | 13 adults with overweight or obesity (crossover) | NR 1,000 mg a day, 6 weeks | Fat-free mass share up 1.34 points |
| Yoshino 2021 | Postmenopausal women with prediabetes and overweight or obesity | NMN, 10 weeks | Reported muscle insulin sensitivity, not weight |
| Pencina 2023 | 30 adults aged 45 and over with overweight or obesity | NMN (MIB-626) 2,000 mg a day, 28 days | 1.9 kg more weight lost than placebo |
The longest of these gave 40 men with obesity 1,000 mg of NR twice daily for 12 weeks [2]. Body composition was measured by DXA and MRI, and NR had no effect on it, nor on resting energy expenditure, fat breakdown or insulin sensitivity.
A 6-week crossover trial in 13 adults with overweight or obesity used 1,000 mg of NR a day [3]. Fat-free mass rose slightly as a share of body weight, 62.65% against 61.32% on placebo, and sleeping metabolic rate rose.
The authors call these minor changes, and they found no effect on insulin sensitivity, liver fat, blood pressure or other metabolic markers.
The 2021 NMN trial in postmenopausal women with prediabetes found better insulin sensitivity and signaling in muscle after 10 weeks [1]. Its reported outcomes were about insulin action, not weight loss.
The one positive weight signal came from a 28-day trial of a microcrystalline NMN tablet in 30 adults aged 45 and over [4]. Body weight fell 1.9 kg more than on placebo (95% CI −3.3 to −0.5), along with lower diastolic blood pressure and cholesterol.
Liver fat, abdominal fat and insulin sensitivity did not change in either group, which makes it hard to say what the weight change consisted of, and the trial was four weeks long.
What the pooled evidence says
A 2026 meta-analysis of oral NMN pooled 15 randomized trials using 250 to 2,000 mg a day for 14 days to 24 weeks [5]. It found no significant effect on body weight or BMI, and none on blood sugar or lipids.
A 2026 systematic review of NAD+ supplementation covered 33 human intervention studies [6]. It found precursors reliably raise NAD+ levels, while effects on metabolic and other health outcomes were mixed and often null.
Regulatory status
NAD+ is not an FDA-approved drug for weight loss or any other use. The FDA lists nicotinamide adenine dinucleotide in Category 1 of its 503A bulk substances list, substances under evaluation that pharmacies may compound under its interim policy [7].
That status covers compounding; it is not a finding that NAD+ works for any purpose. How NAD+ has been dosed in studies is in NAD dosage, and reported side effects are in NAD side effects.
Putting it together
On current human evidence, NAD+ and its precursors have not been shown to cause weight loss: the trials that measured weight or body fat mostly found nothing, and the one exception was small and brief.
Treatments with large, trial-proven effects on weight are covered in peptides for weight loss, and what that loss is made of is in GLP-1 muscle loss.
To compare NAD+ prescribers by format, see the NAD+ injection and nasal rankings.