Results of the Tuna and Water Diet

If you're familiar with celebrity transformations, you might be familiar with Christian Bale's. While seeing this actor bulk up to play Batman was impressive, his Machinist diet was far more shocking. The primary components of his diet for the movie The Machinist were tuna, apples, coffee and water.

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Consuming canned tuna is popular among people trying to lose weight and people trying to bulk up. This is because tuna is primarily protein ⁠— a nutrient that can help you gain muscle and lose weight.

According to the USDA, one can of tuna (about 172 grams, or 6 ounces) has just 220 calories, 5.1 grams of fat and 40.6 grams of protein. There are no carbohydrates in tuna. Like other fish, tuna has a variety of nutrients.

Each can has:

• 9 percent of the daily value (DV) for iron
• 9 percent of the DV for potassium
• 14 percent of the DV for magnesium
• 30 percent of the DV for phosphorus
• 8 percent of the DV for zinc
• 7 percent of the DV for copper
• 205 percent of the DV for selenium
• 6 percent of the DV for riboflavin (vitamin B2)
• 62 percent of the DV for niacin (vitamin B3)
• 22 percent of the DV for vitamin B6
• 84 percent of the DV for vitamin B12

Bodybuilders who follow a tuna diet tend to consume protein shakes and fat-rich foods along with the tuna they consume. In contrast, Christian Bale's weight loss diet involved just one can of tuna and one apple per day.

A single, large apple (around 223 grams) has just 116 calories, 0.4 grams of fat, 0.6 grams of protein and 30.8 grams of carbohydrates. About 5.4 grams of these carbohydrates come from fiber.

Each large apple also contains:

• 5 percent of the DV for potassium
• 7 percent of the DV for copper
• 5 percent of the DV for vitamin B6
• 11 percent of the DV for vitamin C

Water contains no calories, while black coffee has just 2 calories per cup (8 ounces, or 237 milliliters) and trace nutrients. This means that Christian Bale's Machinist diet was made up of a daily intake of around 336 calories, which came from 5.7 grams of fat, 41.2 grams of protein and 30.8 grams of carbohydrates.

According to the _Dietary Guidelines for American_s, most adult men need between 2,000 and 3,200 calories per day. Harvard Health Publishing says that adult men can reduce their calories to 1,500 per day ⁠— and potentially even more under the guidance of a dietitian or other health-care professional. However, even assuming Christian Bale consumed a few cups of coffee each day, he likely wouldn't have ingested more than 350 calories.

Consuming 350 calories is considered a starvation diet by virtually any dietary standard. It's no surprise that Christian Bale's Machinist diet enabled him to lose 63 pounds in just a few months. However, fad diets and rapid weight loss aren't healthy.

In a 2017 interview with the University of Nebraska Medical Center, registered dietitian Rebecca Kraay said, "Crash diets often involve unhealthy calorie restrictions without making true lifestyle behavior changes. So not only are you not getting to the root of the problem, but your weight loss may not be sustainable."

Consuming such a low amount of calories also comes with health risks. If he hadn't been taking supplements, Bale would have undoubtedly ended up with some sort of deficiency ⁠— his Machinist diet certainly doesn't contain all of the vitamins and minerals you need to stay healthy.

There are other dangers to your health associated with crash diets, too. According to a 2016 interview in Esquire with registered dietitian, nutritionist and spokesperson for the Academy of Nutrition and Dietetics Jennifer McDaniel, "The risks of drastic, rapid weight loss include the loss of muscle mass and muscle strength, hormone or electrolyte imbalances, malnutrition, organ dysfunction, dizziness and mood swings."

If you're trying to create a healthy diet, there's nothing wrong with eating apples and canned tuna for weight loss. These are both perfectly healthy and nutritious foods in moderation. However, incorporating a wider variety of foods is much better for your long-term health. Eating different foods not only means a wider variety of vitamins and minerals, but a lower risk of mercury poisoning.

Read more: 10 Low-Calorie Recipes That Are Full of Flavor

When you pick up a tin of tuna, you probably don't think about which type of tuna it comes from. However, this is very important, because some types of tuna are healthier than others.

There are two main types of canned tuna: albacore tuna and skipjack tuna. Canned white tuna is always made from albacore, a fish that contains 0.32 parts per million of mercury. Skipjack tuna is a smaller fish that has less mercury, with just 0.12 parts per million of mercury.

While the Dietary Guidelines for Americans recommends that adults consume at least 8 ounces of seafood per week (based on a 2,000-calorie diet), this shouldn't all come from tuna. In fact, the recommendations state that only 4 ounces per week should come from albacore tuna. However, 8 to 12 ounces per week can come from low mercury fish like skipjack tuna. This is the main reason you should be cautious of consuming a tuna diet for any reason: Too much tuna can lead to mercury poisoning.

Read more: The 9 Safest Seafood Options

Christian Bale's Machinist diet involved the consumption of 6 ounces of tuna, seven times per week. If he was consuming albacore tuna, this means he was consuming more than 10 times the recommended amount per week. If he was consuming skipjack tuna, this amount drops to three and a half times the recommended amount. Cumulatively, this is an excessive amount of mercury, as he was doing it for months on end.

Regardless of whether or not you're on a tuna diet, you should keep an eye on your consumption of mercury-rich foods in order to avoid mercury poisoning. Mercury can be found in a variety of seafood products, including king mackerel, swordfish, Chilean sea bass, mahi-mahi and even shellfish.