Short answer: NAD⁺ is not a weight-loss treatment, it is not studied as one, and you should not buy it expecting to lose weight. The longer answer is more interesting, because one trial did record a weight change — and understanding why that is not the same claim is worth five minutes.
What the one relevant trial found
Researchers randomized adults at risk of age-related conditions, in a 2:1 ratio, to a microcrystalline β-nicotinamide mononucleotide product (MIB-626, two 500 mg tablets twice daily) or placebo for 28 days. The study measured a broad panel: body weight, liver, muscle and intra-abdominal fat, insulin sensitivity, blood pressure, lipids, physical performance and muscle bioenergetics [1].
It found that the NMN product substantially increased circulating NAD and its metabolites, and significantly reduced body weight (P = .008), diastolic blood pressure (P = .034), total cholesterol (P = .004) and LDL cholesterol (P = .007).
So a weight reduction was recorded, and at P = .008 it was not a fluke of the arithmetic. Three things still stop it from being the headline the supplement industry would like it to be. It was one outcome among many in a broad physiologic panel rather than the question the trial was built to answer. It ran 28 days. And it was in adults already at risk of age-related conditions, not a general population looking to lose weight.
Why this is a different category from a GLP-1
A GLP-1 medication is tested in trials where weight loss is the endpoint — that is the question being asked, over a year or more, in thousands of people, with the magnitude of loss reported as the result. NAD⁺ precursors are tested in trials where blood NAD⁺ is the endpoint and weight is one line in a secondary panel.
That difference is not a technicality. It is the difference between “this is what the drug does” and “this moved a bit while we were measuring something else.” Treating them as comparable is how a supplement ends up marketed as a metabolic treatment.
Where the confusion comes from
NAD⁺ is genuinely central to energy metabolism — it is the coenzyme carrying electrons through the reactions that extract energy from food. From there it is an easy step to “more NAD⁺, faster metabolism, less weight,” and it is exactly the kind of step the evidence does not support. A mechanism being real is not the same as an outcome being demonstrated, which is the recurring lesson of this whole category.
The honest framing for insulin sensitivity is similar. NMN increased insulin-stimulated glucose disposal in postmenopausal women with prediabetes [2] — a real result, by the reference method, in a population with a specific metabolic problem. That is worth knowing and it is not a weight-loss claim either.
If you are already on a GLP-1
This is the most common version of the question we see, and the answer is: talk to the clinician who prescribed it. Adding a supplement to a prescription regimen is a conversation to have with the person managing it, not a decision to make from a comparison site — and injectable NAD⁺ in particular is a compounded product with no controlled safety trials of its own.
If you want NAD⁺ for the reasons it does have evidence for, the cheapest and best-supported route is an oral precursor. Just buy it for what it has been shown to do, which is raise NAD⁺ — not for a number on a scale.