Henry Cavill says he has protein smoothies for breakfast and pre-workout supplements to bulk up for roles

• Henry Cavill is an avid user of pre-workout supplements and protein shakes.
• He said they have helped him get in shape to play various roles, including Superman.
• But one dietitian said that just using the supplements is not the trick to getting in shape.

Actor Henry Cavill is an avid user of protein powders and pre-workout supplements.

The "Man of Steel" star told BodyBuilding.com he uses pre-workout supplements and has a cabinet full of supplements wherever he goes. "There's an enormous amount of supplements floating around in whatever place I'm staying," Cavill said.

He said he also incorporates protein powder into his breakfast, snacks, and dessert.

It's not surprising - protein powder and pre-workout are extremely popular among gym goers - but experts caution Cavill's fans that this approach won't work for everyone.

Powder may not be necessary for some people. And supplements can have unpleasant side effects, with questionable benefits.

Cavill has protein oatmeal smoothies for breakfast, and chocolate protein shakes for a snack

For breakfast, Cavill said, he typically blends some oatmeal, berries, and protein powder into a shake.

After a workout, Cavill said he uses 100% grass-fed whey protein, and mixes it with water.

For a dessert, he said he blends chocolate protein powder with milk from Jersey, the island where he grew up.

Protein powder can help some people meet calorie thresholds, but won't change your body alone

Powder can help people meet certain calorie thresholds and ensure that they are getting protein with those calories according to registered dietitian Bonnie Taub-Dix, creator of BetterThanDieting.com - but it isn't some magic potion that leads to bigger muscles.

In fact, Luke Zocchi, Chris Hemsworth's trainer for "Thor," recently said he thinks protein is pointless for muscle-building, as Insider's Gabby Landsverk previously reported.

Taub-Dix said that simply using protein powder or pre-workout supplements will be pointless if you're not working out as much as someone like Cavill.

"When it comes to supplements for muscle growth - no matter what, it's important to build on a foundation food and fitness," Taub-Dix told Insider.

It's more important that you eat a balanced diet of protein, carbs, and fat, while also getting in the right exercise combinations of weight lifting and cardio, she added.

"No matter how many pills, potions or powders you consume - you have to put in the effort it takes to support the body you're looking to attain/maintain."

Supplements can affect digestion

Pre-workout supplements are popular in the bodybuilding space, but some experts say they they shouldn't be regarded as a silver bullet to fitness.

Zocchi, for example, told Landsverk "eating good food and having a calorie surplus are more important" than supplements, which he sees as a waste of money.

Supplements are not regulated by the Food and Drug Administration, which means they can contain ingredients and doses that don't appear on the label.

Fitness influencer Stephanie Sanzo told Insider's Rachel Hosie she stopped using supplements because it was causing digestion issues, and it wasn't really making a big enough difference in her gains to justify it.

"I struggle with irritable bowel syndrome and find that many supplements tend to cause stomach upset (for me personally)," Sanzo told Hosie. "For those who are incorporating supplements into their diet, my biggest advice is to always prioritize your nutrition as no supplements can ever make up for a bad diet."