Experts have warned that gym supplements are often doing more harm than good.
The British Dietetic Association (BDA) says high levels of additional protein can cause side effects.
These can included nausea as well as kidney and liver damage.
They want clearer warnings about what is in the powders and tablets.
Manufacturers say consumers are well protected with only 11 reported reactions in 11 years.
“The more protein in your diet the more you have to get rid of.”
Jane Griffin is a former British Olympic dietician and speaks for the BDA.
“People who have these high protein diets are now running into problems with their kidneys because of the amount of protein they must get rid of.”
The body needs protein for muscle growth and many gym goers use it to try to get bigger quickly.
Gym supplements come under food law so although they have to be labelled properly what is in them can vary.
They are different to medicines which legally have to ensure contents are more specific.
Euromonitor, who research the market size of products, estimate that the sports supplement industry grew 15% last year.
They think one in five people who go to the gym more than twice a week use supplements that can come in the form of powders and bars.
British Department of Health advises adults to avoid consuming more than twice the recommended daily intake of protein (55.5 g for men and 45 g for women).
Most adults will take this in during their normal daily meals.
There have been warnings before, most recently from the food standards agency, who advise people not to take gym supplements containing DMAA.
The stimulant was being sold in some pre-workout and “fat-burning” shakes.
The BDA argue there is now evidence to show excess levels of additional protein taken over a long time can cause health problems.
They believe people can get enough protein naturally from things like chicken and milk.
Richard Cook is 22 and a student from Chesterfield. He has been taking supplements for four years but says he had a bad reaction to one of them.
“It felt like I was on drugs. I was shaking and I got angry. It also had an effect on my girlfriend who didn’t want to be around me when a had taken it.”
Although he still takes protein and creatine gym supplements he says he has cut down from seven to four shakes a day.
“I started thinking to myself, with this one product, why am I taking it when I feel terrible?”
The Health Food Manufacturers’ Association, who represent the supplement industry, says compared to other foods or medicines, gym supplements have an enviable record.