The 10% Paradox: Why Semaglutide and Tirzepatide Don’t Work for Everyone—and What Science Is Doing About It
GLP-1 medications have changed the conversation around obesity and medical weight management.
Semaglutide and tirzepatide have helped many people achieve meaningful weight loss, improve metabolic health, and experience something patients often describe as a noticeable reduction in hunger or “food noise.”
But there is another side of the story that receives far less attention.
Some people take these medications consistently, follow their treatment plan, manage the side effects, and still lose much less weight than expected.
That group is more common than many people realize.
In the STEP 1 clinical trial, 86.4% of participants receiving semaglutide 2.4 mg achieved at least 5% weight loss after 68 weeks. That means roughly 14% did not reach the 5% threshold.¹
In the SURMOUNT-1 trial, approximately 85% to 91% of participants receiving different doses of tirzepatide achieved at least 5% weight loss after 72 weeks.²
More recently, a 2026 cardiovascular, kidney, and metabolic health guideline noted that approximately 10% to 15% of patients in clinical trials demonstrate inadequate weight reduction with GLP-1-based therapy.³
So why does a medication work extremely well for one person and produce a much smaller response in another?
The answer is probably not one simple defect.
It is more likely a combination of biology, genetics, metabolic health, medication exposure, lifestyle, and individual differences that researchers are only beginning to understand.
Why the Same Medication Can Produce Very Different Results
It helps to stop thinking of semaglutide and tirzepatide as medications that simply “turn off appetite.”
Semaglutide acts on the GLP-1 receptor. Tirzepatide acts on both GIP and GLP-1 receptors.
These pathways influence appetite, fullness, food intake, glucose regulation, digestion, and communication between the digestive system and the brain.
But people do not have identical biology.
The same dose of medication does not necessarily create the same response in every person.
Understanding Individual GLP-1 Response
Think about two people listening to the same radio station. The signal being transmitted may be identical, but the quality and volume of what each person hears can be different.
Something similar may happen with metabolic signaling.
For one person, GLP-1-based therapy may produce a dramatic reduction in hunger and food intake.
Another person may notice moderate changes.
Someone else may barely notice a difference.
Researchers are now trying to understand why.
Genetics May Be Part of the Story
One of the most interesting areas of research involves the GLP-1 receptor itself.
Researchers have identified genetic differences in GLP1R, the gene associated with the GLP-1 receptor, that may influence how some people respond to these medications.
A 2025 study of people with severe obesity treated with semaglutide found that a GLP1R genetic variant and sex were associated with differences in the rate of weight loss.⁴
Larger genetic studies published in 2026 have also identified genetic variants associated with differences in weight-loss response to GLP-1 medications.⁵
Can Genetics Predict Semaglutide or Tirzepatide Results?
This does not mean we can currently perform a simple genetic test and predict exactly how much weight someone will lose.
We cannot.
It does suggest, however, that medication response may be influenced partly by biology that exists long before someone ever takes their first injection.
The future of obesity medicine may eventually involve identifying which metabolic pathways and medications are most likely to work for an individual patient rather than relying primarily on trial and error.
Metabolic Health Matters Too
Genetics is only one piece.
A 2026 systematic review examining low weight-loss response to GLP-1 and GIP-based medications found several factors associated with differences in treatment response, including baseline weight, BMI, blood sugar control, insulin resistance, medication adherence, lifestyle factors, age, sex, and potentially genetic differences.⁶
That is important because two people can have the same BMI while having very different metabolic profiles.
One may have significant insulin resistance.
Another may have poorly controlled diabetes.
Another may be taking medications associated with weight gain.
Another may have an underlying endocrine condition.
Another may simply require more time or appropriate dose escalation before the full effect of treatment becomes apparent.
Why Medical Weight Management Should Look Beyond the Scale
This is one reason medical weight management should involve more than prescribing medication and checking the scale a few months later.
A patient’s metabolic health, medication response, medical history, and other individual factors can provide important context when results are slower than expected.
The Body Also Adapts to Weight Loss
There is another challenge. Your body is not passive during weight loss.
As body weight decreases and calorie intake falls, energy expenditure can decrease as well. This phenomenon is often referred to as metabolic adaptation or adaptive thermogenesis.
A smaller body naturally requires fewer calories, but additional changes in energy expenditure can also occur during weight loss.
That does not mean someone’s metabolism has “shut down.”
It does mean that weight loss rarely follows a perfectly straight line.
Why Weight-Loss Plateaus Can Happen
Early progress may slow.
Plateaus can occur.
Hunger, activity levels, sleep, muscle mass, nutrition, and energy expenditure can all influence what happens next.
For some patients, the medication effect is strong enough to produce substantial weight loss despite these adaptations.
For others, progress may be slower and require adjustment of the overall treatment strategy.
Sometimes the Question Is Not “Why Isn’t the Drug Working?”
Sometimes the better question is:
“What Else Is Influencing This Patient’s Weight?”
When someone has an unexpectedly limited response, clinicians may need to look beyond the medication itself.
Depending on the individual, that evaluation may include:
Treatment duration
Medication adherence
Dose progression
Nutrition
Protein intake
Physical activity
Sleep
Alcohol intake
Other medications
Glucose control
Insulin resistance
Thyroid disease
Other medical or endocrine conditions when clinically indicated
This is very different from assuming that the person “must not be trying.”
Obesity is a chronic disease influenced by neurological, hormonal, metabolic, environmental, behavioral, and genetic factors.
A medication can address important parts of that biology without necessarily correcting every factor affecting a person’s weight.
Before Calling Semaglutide or Tirzepatide a Failure
There is also an important issue of timing.
GLP-1-based medications are typically increased gradually, and meaningful weight loss may continue for many months.
Current guidance recognizes that assessing response may require several months of appropriate treatment and dose escalation.³
Questions to Ask When GLP-1 Weight Loss Is Slower Than Expected
Before deciding that someone has experienced an inadequate response, a clinician may need to ask:
Has the medication been taken consistently?
Has the patient reached an appropriate tolerated dose?
Has enough time passed to evaluate the response?
Are side effects preventing adequate nutrition or medication adherence?
Are other medications contributing to weight gain?
Are there metabolic or medical conditions that need attention?
Has body composition changed even if the scale has slowed?
Has physical activity changed as calorie intake has fallen?
The answers can change the treatment plan.
The Future Is Precision Obesity Medicine
The future of medical weight management is unlikely to be one medication for everyone.
Researchers are studying additional hormone pathways, combination approaches, multi-receptor medications, amylin-based therapies, and other strategies that may expand treatment options.
Genetics may eventually help clinicians predict medication response before treatment begins.
Biomarkers may help identify different obesity phenotypes.
And medications targeting multiple metabolic pathways may provide options for people who respond poorly to today’s treatments.
Beyond Semaglutide and Tirzepatide
We are already seeing the beginning of this shift.
Semaglutide primarily targets the GLP-1 pathway.
Tirzepatide targets both GIP and GLP-1.
Other investigational treatments are exploring additional metabolic pathways.
The larger question is changing from:
“Does this medication work?”
to:
“Which treatment strategy is most likely to work for this particular patient?”
What This Means at Vital Bloom Concierge Medical Care
At Vital Bloom Concierge Medical Care, medical weight management is not simply about prescribing a GLP-1 medication and waiting for the scale to move.
Treatment should be evaluated over time.
If progress is slower than expected, the answer should not automatically be to blame the patient or simply increase medication without understanding what is happening.
Instead, the treatment plan may need to be reassessed.
A Personalized Approach to GLP-1 Weight Management
That can include reviewing:
Medication response
Dose and duration
Nutrition
Physical activity
Metabolic health
Side effects
Other medications
Lifestyle factors
Other medical concerns when appropriate
For some people, semaglutide may be effective.
For others, tirzepatide may be more appropriate.
For others, a different strategy may ultimately be needed.
Individual treatment decisions should be based on a medical evaluation, health history, treatment response, and clinical appropriateness.
Understanding the “10% Paradox”
Perhaps the most important lesson from the “10% paradox” is that average clinical-trial results do not predict exactly what will happen to an individual patient.
An average weight loss of 15% or 20% does not mean every patient will lose that amount.
Some will lose considerably more.
Some will lose less.
And a smaller group may experience a limited response despite appropriate treatment.
A Limited Response Does Not Automatically Mean Failure
That does not automatically mean the patient failed.
It may mean the treatment strategy needs another look.
As researchers learn more about genetics, metabolic signaling, insulin resistance, body composition, treatment adherence, and individual differences in medication response, obesity medicine is moving toward something far more useful than a one-size-fits-all prescription.
The goal is not simply finding a medication that works.
It is finding the right strategy for the person taking it.
References
Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. New England Journal of Medicine. 2021;384:989-1002.
Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine. 2022;387:205-216.
American Heart Association, American College of Cardiology, American Diabetes Association, American Society of Nephrology. 2026 Guideline for the Prevention, Detection, Evaluation, and Management of Cardiovascular-Kidney-Metabolic Syndrome. Journal of the American College of Cardiology. 2026.
Phan A, et al. A GLP1R Gene Variant and Sex Influence the Response to Semaglutide Treatment in Patients With Severe Obesity. Obesity. 2025;33(7):1237-1242.
Auton A, et al. Genetic Predictors of GLP1 Receptor Agonist Weight Loss and Side Effects. Nature. 2026.
Gaskin PS, Chami PS. Low Weight Loss Response to Incretin Analogs: A Systematic Review. Obesity Reviews. 2026.
Medical Disclaimer
This article is for educational purposes only and is not a substitute for individualized medical advice, diagnosis, or treatment. Semaglutide, tirzepatide, and other prescription medications should only be used when clinically appropriate and under the supervision of a qualified healthcare professional. Individual responses to treatment vary.
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