What the Scale Does Not Show

I read the Specific, Measurable, Achievable, Relevant, Time-bound (SMART) trial¹ through two lenses at once. As a health care executive who has spent more than a decade building an association management company serving dozens of medical specialty societies, I am looking for what it tells clinicians. But I am also reading it for myself. For 45 years, I have been navigating complex kidney disease. My fourth transplant was followed by abrupt physiologic changes—prednisone and menopause colliding at once—and the weight gain and anxiety that came with it.

Those two perspectives are inseparable for me, and together they shape what I believe should be the universal question in health care: How can patients live their best lives while also achieving the best medical outcomes? The patient is my purpose.

SMART asks a specific pharmacologic question. In adults with CKD, overweight or obesity, and no diabetes, does 24 weeks of semaglutide alter body composition in ways that distort our most common kidney-function tests? Heerspink et al. answer with reassuring clarity for a transplant patient like me. Body weight fell by roughly 9 kg versus placebo. Both fat mass and lean mass declined. And yet—across creatinine-based, cystatin C-based, and iohexol-measured GFR, those compositional shifts did not meaningfully affect the kidney function the investigators were tracking.

For clinicians monitoring CKD progression in patients on incretin therapy, this is important. The tools we use to follow kidney function still work when patients lose ten percent of their body weight. In a moment when semaglutide is becoming popular and easily accessible, knowing our laboratory test values remain interpretable while on the medicine is reassuring.

This article gives me relief and hope. After my transplant, my body did what transplanted bodies often do under high-dose immunosuppression: It gained weight quickly, on the heels of being underweight for an extended time being sick. A glucagon-like peptide-1 (GLP-1) helped me reverse the post-transplant rapid gain. This allowed me to exercise and rebuild my health quicker.

SMART also showed that when semaglutide lowers BP when patients shed excess fluid—not fat or muscle. That is great news for kidney patients. Many of us, in end-stage disease and post-transplant, carry too much sodium and water because our kidneys cannot clear them perfectly, and that hidden fluid load is a quiet driver of hypertension and cardiovascular risks. This does not replace the need to stay hydrated on the medicine.

The finding I keep returning to is the one the authors handle most carefully: the lean mass change. SMART reports a 2.5 kg loss of lean mass alongside a 3.9 kg loss of fat mass. The investigators are transparent about what they did not measure—muscle volume, muscle strength, physical performance—and about who is most vulnerable if those losses compound: older patients with CKD, patients on long-term immunosuppression, patients whose mobility is already fragile. Their guidance is direct: These glucagon-like peptide medicines should be paired with age-appropriate resistance training and adequate nutrition.

Before starting a GLP-1 post-transplant, I hired a certified trainer and committed to 5-day-a-week strength training. I did not load up on protein supplements; I ate the amount my doctors recommended. The fat came off. The muscle did not. I no longer take BP medications. I am measurably stronger than I was before the GLP-1, despite being postmenopausal.

This points to a prescribing gap SMART implies. The trial answered the kidney-safety question. The body-composition question is only half answered by the medication. The other half is answered by what we ask patients to do alongside it, which is also empowering for patients.

For patients like me, the implications are practical. Read everything. Use the critical thinking you developed as your own advocate. Ask your clinical team what resistance training looks like for your body, your stage of disease, your transplant status. In my case, I cannot do sit-ups or crunches—but there are hundreds of other abdominal exercises I can do. Ask about nutrition that supports muscle preservation in the context of your kidney function. Treat the GLP-1 as one tool in a broader plan to care for your kidney.

For clinicians, the study underscores why patients must understand how to live healthfully with their own histories in mind. The patients most likely to benefit—those with CKD, cardiovascular disease, obesity-related complications, or a family history like mine of diabetes and heart disease deserve medicines like this to live healthier lives.

SMART is a careful, useful, generously transparent trial. It moves the field forward, and like every sterling clinical trial, it invites us to keep asking what the numbers cannot show—and to keep building the care plans that turn good pharmacology into good lives.

The patient is the purpose.

Supplementary Material

cjasn-21-1113-s001.pdf ^{(160.7KB, pdf)}

Disclosures

Disclosure forms, as provided by each author, are available with the online version of the article at http://links.lww.com/CJN/C773.

Author Contributions

Writing – original draft: Elizabeth Ann Schumacher.

Writing – review & editing: Elizabeth Ann Schumacher.

Funding

None.