Serena Williams’ Former Coach Says They ‘Fought’ Over Weight After Pregnancy as She Turned to GLP-1 Treatment

Patrick Mouratoglou, Serena Williams’ former coach, said he had “a few fights” with the tennis champion about her weight after she returned from pregnancy, arguing that extra pounds were affecting her movement and increasing her risk of injury.

In an interview with The Guardian, Mouratoglou said he raised the issue not as a comment on Williams’ appearance but as a performance concern. “Listen, this is not a comment on how you look. It’s not my problem,” he told her. “But tennis is a sport in which you can’t afford to be overweight. First of all, the pressure on your joints and everything is so big that your chances become much higher. The second thing is it’s a sport in which you change directions all the time and with a lot of speed. Even one kilo overweight is a lot.”

Mouratoglou, who coached Williams during a period in which she won 10 of her 23 Grand Slam singles titles after hiring him, said the issue arose after Williams’ pregnancies, noting the body “is not going to bounce back the same as before” as athletes age. He singled out movement as critical at the top level of the sport and compared elite players’ mobility, citing Carlos Alcaraz, Jannik Sinner and Novak Djokovic.

Williams, 43, has publicly acknowledged using a GLP-1 medication marketed as Ro to lose weight. Her role as a paid spokesperson for the company and information on the company’s website state she lost 31 pounds in eight months. GLP-1s, short for glucagon-like peptide-1 receptor agonists, are a class of drugs used to treat type 2 diabetes and, more recently, to support weight loss when prescribed by clinicians.

On the television program Today, Williams discussed her decision to use the medication after difficulty maintaining what she described as a “healthy” weight following the births of her daughters, Olympia in 2017 and Adira in 2023. She has also publicly addressed stigma surrounding GLP-1s, rejecting the notion that using such medications is a shortcut or a sign of laziness.

Mouratoglou said he sometimes clashed with Williams over his assessment. “We had a few fights about it. I remember she did not like when I said that because she thought I was judging her. But I kept telling her, I don’t care about your look. It’s not my job. My job is your tennis,” he said. Asked whether he wished she had been in the same physical condition earlier in her career, Mouratoglou stopped short of dwelling on the past: “I’m not the type of guy who’s looking back and having regrets. But, yeah, if she would have been in this position physically, the results would have been better.”

Williams has continued to speak about her health and body openly. Last June she posted that she had undergone a skin-tightening procedure. Her public comments and endorsement deal highlight how elite athletes’ personal medical choices intersect with wider public conversations about weight-management medications.

Discussions about GLP-1s have intensified as their use has broadened beyond diabetes treatment to address obesity and weight regain, including after pregnancy. Medical societies recommend that such treatments be considered and managed by health care professionals, with attention to potential benefits and risks for each patient.

Mouratoglou’s remarks underscore the tension that can arise between athlete care and personal privacy as retired and current champions navigate comeback attempts, aging bodies and the evolving landscape of weight-loss therapies.