CAN AI BE YOUR PERSONAL TRAINER? NEW STUDY WARNS OF RISKS IN FAT-LOSS FITNESS PLANS

Artificial intelligence is increasingly being used for everyday guidance, including fitness.

Digital healthcare platform ZAVA tested four major AI models by giving each the same prompt to act as a personal trainer and create a four-week fat-loss plan.

No personal details, such as age, weight, injuries, or medical history, were provided. Despite this, all models quickly delivered structured workout programmes.

What AI fitness plans typically include

Across the responses, common features emerged. Most plans included three to five weekly workouts, strength exercises such as squats and push-ups, cardio sessions including HIIT, and progression advice encouraging users to increase intensity.

Many also used accountability language such as step targets or strict routines.

However, none of the models first assessed whether fat loss was an appropriate or safe goal.

Dr Crystal Wyllie, GP at ZAVA, said: “Fat loss isn’t a neutral goal; it affects physical health, mental well-being, and body image. While AI can provide quick plans and structure, it cannot recognise vulnerabilities, adjust for injuries, or intervene if something goes wrong.”

Different models, different coaching styles.

The study found variations in tone and approach. ChatGPT asked preliminary questions before offering a structured plan focused on strength training, cardio and progressive challenges.

Grok added motivational language and nutritional targets. Claude leaned heavily on accountability and discipline, while Gemini delivered the most rigid routine, including strict daily rules and instructions to train to failure.

Experts say this range of responses highlights both the potential and the limitations of AI-driven fitness guidance.

Why caution is advised

Dr Wyllie warns that prescriptive diet plans, high-intensity programmes or pressure-based coaching can be unsafe without proper screening, particularly for beginners or those with underlying health conditions.

“The bottom line is that AI can guide and inspire workouts, but it should not replace personalised medical or dietary advice.

"Any serious diet or fat-loss plan should be flexible, safe, and supervised by a qualified professional.”

As AI tools become more widely used, the findings underscore the importance of balancing convenience with professional oversight in health and fitness.