5 Eggs, Zero Breakfast Carbs, and 20 Extra Pounds: Inside Alexander Skarsgård's 'The Northman' Transformation

The Hollywood star had already transformed his body once with trainer Magnus Lygdback. Years later, the pair reunited to create a very different physique for a brutal Viking revenge story through months of carefully controlled eating and training.

Alexander Skarsgård wanted his character, Amleth, to look like a man capable of surviving the violent world at the center of "The Northman," and creating that physique required more than simply adding muscle.

The Swedish actor played the Viking prince in Robert Eggers' film, which follows Amleth on his quest to avenge his father's death. For the physical transformation, Skarsgård turned to someone who already knew exactly how his body responded to intense training: celebrity trainer Magnus Lygdback.

Their history stretched back to "The Legend of Tarzan," when they spent close to a year working together to prepare Skarsgård to play the title character.

Lygdback remembered seeing how invested Skarsgård was in the idea of a Viking film, which eventually became "The Northman" and told the actor to call if it ever became a reality. That call finally came in the middle of 2019, and by December, the two were working together again.

This time, however, they were not trying to recreate the leaner, more agile physique Skarsgård had developed for "The Legend of Tarzan." Lygdback explained:

"In 'Tarzan,' he was more slim and agile and this time he gained about 20 pounds because we wanted a thicker and more imposing look."

Building Amleth Without Simply Bulking Up

Putting approximately 20 pounds on an actor who was naturally lean required Lygdback to keep a close eye on how Skarsgård's body was changing. The Hollywood star remained in a daily calorie surplus so he could add size without continuing to lose body fat, which Lygdback measured every week.

"I like to monitor my actors," the celebrity trainer revealed, noting that the measurements helped ensure Skarsgård was neither becoming too lean during the buildup process nor accumulating too much body fat.

The pair continued adding mass until it was time to sharpen the physique they had built. Skarsgård then spent three weeks dieting before filming.

Their previous work together made the compressed timeline possible. The trainer still had notes from "The Legend of Tarzan" and already understood how Skarsgård responded to his methods, giving them an advantage they had not had during their first collaboration.

Core exercises were also done daily, with the specific area being trained changing as part of the overall split rather than repeatedly stressing the same muscles.

Knowing his body was only part of the equation, however. Amleth's physical demands also dictated how they trained. Skarsgård would be moving extensively, performing many of his own stunts, and repeatedly handling weapons during the production. Consequently, his shoulders became a particular focus.

"We needed to make sure that we prepped his shoulders for all the fighting, swinging a sword and an ax," Lygdback said. Extra accessory exercises were incorporated to prepare that area, while the broader objective remained straightforward — add strength and thickness across his frame.

Five or Six Training Days and a Four-Day Strength Split

The program combined several forms of exercise, but strength work followed a four-day split. Day one targeted the legs, followed by chest and the front of the shoulders on day two. The third day focused on the back along with the rear and outside portions of the shoulders, while arms were trained on day four.

Although Lygdback scheduled training across all seven days of the week, that did not mean Skarsgård actually exercised seven consecutive days. Rest was taken whenever necessary, and in practice, the actor generally trained between five and six days each week.

Cardiovascular exercise and core work were incorporated alongside the strength sessions. Depending on the day, the cardio could be performed at high intensity or at a more conventional pace.

Core exercises were also done daily, with the specific area being trained changing as part of the overall split rather than repeatedly stressing the same muscles. The routine reflected Lygdback's preference for established fundamentals over constantly introducing new exercises. He said:

"I'm not one who is trying to reinvent the wheel and come up with new fancy exercises. I believe in sticking to a routine, the fundamentals, and getting really good at that."

Breakfast Started With Four or Five Eggs and No Carbs

Training was only one side of Skarsgård's transformation, as his meals were structured just as deliberately. Lygdback favored beginning the day with a high-protein meal, typically built around eggs.

For the Hollywood star, that meant eating four to five eggs at breakfast. During his three-week diet ahead of filming, there was one notable omission from that first meal — carbohydrates. The actor followed breakfast with a protein-heavy snack.

Lunch then introduced a broader combination of protein, slow-digesting carbohydrates, vegetables, and "good fats." Another high-protein snack came later, while dinner included protein, carbohydrates, vegetables, fiber, and more good fats.

Rather than treating food and training as separate pieces of the transformation, the celebrity trainer adjusted the process according to the labor Skarsgård's body was doing.

That approach was particularly important when physical changes had to happen within the limited timetable of a movie production.

The weekly body-fat measurements helped determine whether the buildup was progressing as intended before the final dieting period began. Their preparation appeared to be approaching its final stage in early 2020.

Skarsgård had been working on "The Stand" in Vancouver, with Lygdback traveling there to continue his training, before the pair moved on to Northern Ireland ahead of "The Northman."

The Transformation Began With a Plan, Not a Shortcut

For Lygdback, preparing an actor for such a demanding role was not simply a matter of supplying a workout sheet and meal schedule. He also considered how the individual responded psychologically to training.

That included what motivated them and how far they could be pushed without approaching the process in the wrong way. The specific program could then be shaped around where the actor's starting point, the physique required for the character, and any skills the role demanded.

That approach was particularly important when physical changes had to happen within the limited timetable of a movie production. Lygdback stressed that trying to rush past the fundamentals increased the likelihood of injury once training became more demanding. He explained:

"As long as you have a plan, you can be patient. You can't rush things."

He also researched potential clients and spoke with them before accepting projects because months of preparation depended on their willingness to follow through.

A transformation could require six months of training followed by another six months of filming, making the actor's commitment central to the process. With Skarsgård, that commitment had already been tested during "The Legend of Tarzan."

But their second major transformation asked for something different — not the lean, agile body they had previously created, but roughly 20 additional pounds and a thicker frame capable of supporting months of fighting, stunt work, and weapon handling.

Skarsgård eventually arrived on the set of "The Northman" with the heavier, more imposing physique that he and Lygdback had envisioned for Amleth.