Posted by Mark Nessim
Reviewed by Dr. Mark, Physician & Formulator.
An argument about counting to forty
On August 5, 2026, BioSpace reported that a two-year legal fight between Eli Lilly and the FDA was coming to a head, and that the whole thing turns on arithmetic.
The FDA's regulation defines a protein as an alpha amino acid polymer with 40 or more amino acids. Retatrutide — Lilly's triple-agonist obesity candidate, which is investigational, not FDA approved, and not commercially available — has 41 amino acids, according to Lilly's own complaint. The FDA counted differently, concluding it does not have 40 or more alpha amino acids, and classified it as a drug rather than a biologic. Lilly's brief replies, more or less in full: “41 is plainly greater than 40.”
The distinction is worth a great deal. A biologics licence carries twelve years of market exclusivity; a new drug application carries five. Nothing about the molecule changes either way. The courts have so far returned a mixed result, Lilly has appealed, and the company still expects to file for approval in the first quarter of 2027. (If you want the wider context on this compound and the unregulated market that has grown up around it, we wrote about that separately in Can You Buy Retatrutide Yet?)
The same thing happens to your protein powder
Categories, not substances, decide outcomes throughout this field — and one category decides whether the protein you drink every morning is bought with taxed money or untaxed money.
To the IRS, a protein powder is a food. Food is not a qualified medical expense, and no amount of arguing about whey isolate will move it. What can move it is a Letter of Medical Necessity: a clinician documenting why this particular nutrition is being used to treat or manage a specific medical condition, rather than consumed for general health.
With that letter, the identical tub may become an eligible HSA or FSA expense. Without it, it isn't. The powder is unchanged. The paperwork is what moved.
Two things worth being precise about, because they are commonly muddled:
- A card terminal is not an eligibility determination. Whether an HSA or FSA card happens to process at a given merchant is a function of that merchant's category code, not of whether the IRS considers your purchase qualified. The letter is what protects you, not the swipe.
- Eligibility is never guaranteed in advance. Plans differ, administrators differ, and documentation requirements differ. We are not able to give tax advice; your plan administrator can tell you what your specific account covers.
Habthera's checkout partner, Flex, runs the questionnaire that produces the letter, and it takes about three minutes. You can see how that works on our HSA/FSA page.
While we're on the subject of counting things
The protein numbers are less contested than the amino-acid ones, and rather more relevant to most people reading this.
A 2026 review in Metabolites — “Lean Mass and Musculoskeletal Preservation in GLP-1-Based Obesity Treatment” — puts the working consensus at roughly 1.2 to 1.5 grams of protein per kilogram of body weight per day during active weight loss.
The same review quantifies the gap between that target and reality. In a cross-sectional study of current GLP-1 receptor agonist users, mean protein intake was 77.3 g per day, against desirable intakes of 74 to 169 g per day across participants. Only 43% reached even the 1.2 g/kg floor.
The honest caveat comes from that same paper: direct randomised evidence on protein supplementation during GLP-1 therapy does not yet exist. A registered trial is expected to report initial data in 2027. What does exist is the intake data above, plus meta-analytic evidence from weight-loss trials generally that higher protein intake attenuates loss of muscle mass. We have written more on the practical side of hitting those numbers in How Much Protein Do You Actually Need on a GLP-1?
Protein is also not the whole answer. The 2025 joint advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association and The Obesity Society is direct about it: protein without structured resistance training is not enough. Nutrition is the part that is easy to get right. The lifting is still the lifting.
On creatine, described accurately
ASP-1 carries 3 g of creatine monohydrate, and the evidence there deserves describing accurately rather than enthusiastically.
A 2024 systematic review and meta-analysis in Frontiers in Nutrition pooled 16 randomised controlled trials covering 492 adults. Creatine showed a modest but statistically significant benefit for memory (SMD 0.31). It showed no significant improvement in overall cognitive function or in executive function, and the authors rated the certainty of the evidence for several of those outcomes as low.
That is the real shape of it. Naming what an ingredient does not do is what makes the rest of a claim worth believing — a standard we applied at length in BPC-157: What the Evidence Actually Says.
One scoop is the whole protocol
The reason all of this arrives as a single scoop is that most people managing appetite changes have no appetite for a supplement schedule either. 25 g of total protein — 20 g whey isolate plus 5 g collagen peptides — along with the creatine, magnesium, zinc, methylated B-12, L-glutamine and a probiotic. Once, in the morning, in water.
“I've been on a GLP-1 medication for a few months, and getting enough protein has definitely been a challenge… It's become an easy way for me to stay on top of my protein intake on days when I'm not very hungry.”
— DAVID D., Verified buyer
The Lilly case will be settled by people arguing about the letter alpha. The consumer version is simpler: a letter from a clinician, a few minutes at checkout, and a category that changes while the product stays exactly the same.
This article is for general information and is not medical, tax, or legal advice. Decisions about your treatment belong with your own clinician, and questions about what your HSA or FSA covers belong with your plan administrator.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
