Tennis legend Serena Williams has revealed that she’s lost 31 pounds over the last eight months using a GLP-1 medication. Williams has now joined the growing number of women who are turning to these drugs to manage weight and metabolic health.

For Williams, the journey to make this decision was tough. She explained that even when she trained her hardest after her second baby, she just couldn’t lose the weight she wanted to. Although many people associate GLP-1 medication as a “shortcut”, Williams said that wasn’t the case. She simply wanted to feel like herself again in her own body. Her openness has sparked renewed conversation about the benefits and the risks of these drugs, especially as more women consider them.

To help unpack the science and safety, 21Ninety spoke with Dr. Bronwyn Holmes, M.D., a board-certified physician with specialized expertise in chronic conditions, cardiometabolic health, and aging-related hormonal shifts. 

The Side Effects That Too Often Get Overlooked

GLP-1 medications like Wegovy and Zepbound are most commonly prescribed for diabetes and weight management, but Dr. Holmes says patients need to be fully aware of their side effects.

“The most well-established long-term effects we’re seeing involve the gastrointestinal system,” she explained. “Nausea, vomiting, constipation, and diarrhea occur in up to 40 percent of patients taking these medications. What concerns me more is that these side effects cause over 10 percent of patients to discontinue treatment entirely. From a functional medicine perspective, this tells us we’re not adequately preparing patients for the journey or supporting them through the adjustment phase.”

Beyond short-term discomfort, the risks may build over time.

“Gastrointestinal concerns extend beyond temporary discomfort,” Dr. Holmes shared. “We’re seeing reports of increased risk of intestinal obstruction, particularly in diabetic patients using GLP-1s long-term – with a 4.5 times higher risk compared to other glucose control medications. The risk appears to increase over time, peaking around 1.6 years after initiation.”

GLP-1 and Vision Complications

One of the lesser-known risks involves vision changes, which can be both sudden and irreversible.

“The vision-related side effects are particularly concerning and represent an area where we’re still learning. Recent studies have identified several serious complications,” Dr. Holmes noted.

She also mentioned one especially alarming condition that patients need to be on the lookout for.

“Most alarmingly, we’re seeing cases of nonarteritic anterior ischemic optic neuropathy (NAION) – essentially an ‘eye stroke’ that can cause sudden, permanent partial vision loss,” she warned. “In one study, seven out of nine patients with vision problems experienced this condition. What’s particularly concerning is that these effects can occur as soon as the day after starting treatment.”

Do Women Experience Different Side Effects?

With Williams’ story at the center, many women are wondering, does gender make a difference in how these drugs work?

“The research suggests women may experience gastrointestinal side effects more frequently than men, while men may report different tolerability patterns,” Dr. Holmes said. “This aligns with what we know about how hormonal factors and body composition influence drug metabolism. However, we need more robust studies to fully understand these differences. As someone who works extensively with women navigating midlife metabolic changes, I always consider how estrogen fluctuations might interact with these medications.”

Social media has been buzzing with talk of “microdosing” GLP-1 medications. Microdosing is simply taking smaller-than-prescribed doses to minimize side effects or stretch out prescriptions. But Dr. Holmes has a firm warning.

“I cannot emphasize strongly enough how concerning the trend of microdosing GLP-1 medications is,” she warned. “These medications have specific dosing protocols developed through rigorous clinical trials. When patients self-adjust doses to manage side effects or extend insurance coverage, they’re essentially conducting uncontrolled experiments on themselves.”

She explains that microdosing can lead to unpredictable blood sugar fluctuations, loss of therapeutic benefit, and even masked side effects that worsen over time.

Another rising concern is people turning to online vendors or compounded “research-grade” versions of GLP-1 drugs. Dr. Holmes calls this a serious safety risk.

“This practice represents a significant patient safety concern,” she said. “‘Research-grade’ versions obtained online bypass crucial safety measures: no quality control or potency verification, unknown ingredients or contamination, lack of proper storage and handling, absence of medical supervision for dosing and monitoring, and no recourse for adverse events.”

Why GLP-1 Lawsuits Are Piling Up

The risks aren’t just theoretical. There are already thousands of lawsuits related to GLP-1 drugs.

“The lawsuits primarily focus on insufficient warnings about serious adverse events, particularly: severe gastroparesis (stomach paralysis) that may persist after discontinuation, vision complications, especially in diabetic patients, suicidal ideation and mental health effects, and severe dehydration leading to hospitalization,” Dr. Holmes shared.

For patients, she stresses, this highlights the importance of thorough informed consent and ongoing medical supervision. These are things that can’t be skipped in the rush to “get results.”

Before considering a GLP-1 medication, Dr. Holmes recommends women go in prepared with specific questions such as the following:

  • Do I have any risk factors for vision complications, particularly diabetic retinopathy?
  • What specific monitoring will you provide throughout my treatment?
  • How will we address side effects if they occur?
  • What are the criteria for discontinuing this medication?
  • How does this medication interact with my other health conditions and medications?
  • What happens to my metabolic health when I stop taking this medication?

“The key is approaching these medications with both scientific rigor and deep respect for the individual sitting in front of us,” she advised. “They’re powerful tools, but they require the guidance of experienced healthcare providers who understand both their potential and their limitations.”

Williams’ openness about her own GLP-1 journey adds visibility to a conversation that many women are already having quietly. These medications may be powerful, but as Dr. Holmes makes clear, they’re not simple and not without risk. If you’re considering them, do so with full knowledge, trusted medical support, and a plan for the long-term.