Around 1,000 NHS workers have been injured while caring for obese patients over the last five years, Freedom of Information data shows.
One nurse was signed off with neck, back and shoulder pain after having to hold a patient's breasts during an ultrasound, The Sun newspaper reported.
Another worker's cheek was bruised while washing the stomach of a 42st patient.
In other cases, a staff member at Great Ormond Street Hospital suffered a back injury lifting a 15st child and a nurse got a back sprain helping to move a 29st patient for an X-ray.
The data showed at least 923 staff were hurt caring for obese patients between 2011 and 2015.
Some of the injuries included sprained necks, hernias, kicks to the ribs, muscle tears, trapped fingers and slipped discs, the newspaper said.
It calculated that four years and seven months were lost in sick days.
Tam Fry, of the National Obesity Forum, said: "Some hospitals have been negligent in trying to get away with using standard equipment for obese people and the result is something is going to snap. These figures should send the NHS into shock."
Kim Sunley, of the Royal College of Nursing, said: "Employers need to ensure staff have the right equipment and training to reduce physical strain, particularly since the number of very heavy patients is increasing.
"Having enough available staff to help patients and other staff would also ease the physical pressures. Many nurses with back problems need time off."