Jillian Michaels said weight loss is like paying off debt, but the reality isn't always so simple

• Jillian Michaels said weight loss is like paying off debt - you work harder for a period, then can relax.
• But dietitians told Insider this analogy is "over-simplified," and weight loss is more nuanced.
• While you can control your spending, other factors affect a person's weight, they said.

Successful weight loss is largely affected by mindset, and approaching it like paying off debt could be the key, personal trainer Jillian Michaels told Insider.

She explained that it's something you have to work harder to do, but once it's done you can relax more.

"To lose weight you simply eat less and move more," the former "Biggest Loser" coach said.

"It's a lot like paying off a debt. When you are paying it off you might work two jobs to pay off the debt and make ends meet. Once the debt is paid, you can drop one of those jobs. Same with weight loss," she said, adding that once you're in maintenance mode it gets easier.

But dietitians told Insider that weight loss isn't always so simple.

Factors affecting weight are sometimes out of our control

While it's true that weight loss comes down to managing your energy balance (taking in fewer calories than you're expending), thinking of it like debt isn't accurate, according to dietitians.

"Thinking of balancing calories as you would balance your finances may enable some people to achieve the results they desire," registered dietitian Ro Huntriss told Insider, adding that a multitude of factors affect weight management.

Unlike our spending habits, factors affecting our weight are sometimes out of our control, including genetics and upbringing, according to registered dietitian Nichola Ludlam-Raine.

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"I don't necessarily agree that weight loss should be viewed as paying off a debt, as healthy eating practices and increasing activity levels may then be seen as more of a punishment, which may be less likely to be sustained," Ludlam-Raine told Insider.

Weight loss is affected by lots of different factors, dietitians say

While "eat less and move more" is technically correct advice for weight loss, Huntriss said it's an "over-simplified" approach.

Ludlam-Raine said weight loss is nuanced - for some people, new healthy habits become a lifestyle that gets easier over time, but for others it can get more difficult and they hit a plateau or their progress slows down.

"This is because as the body loses weight and becomes smaller, your metabolic rate (the rate at which your body burns calories) also slows, meaning exercise often has to be increased and calorie intake further reduced," she said, adding that you shouldn't drop your calories lower than 1,200 per day unless medically advised.

Weight maintenance also takes work

Michaels, whose focus is maintaining her weight and fitness levels, does no more than two hours of exercise a week. That could be enough for weight loss if you work out effectively, she said, but you'd get quicker results if you moved more.

"As long as I am eating smart - not overeating and eating real food - it works perfectly for me," she said. "A person wanting to lose weight could do four sessions of 30 minutes a week - their results might just come a bit more slowly than if they trained six times a week."

While losing weight is generally considered to be the hardest challenge, it's often maintaining a healthy weight afterwards that people find most difficult, according to Ludlam-Raine.

"Weight maintenance takes work," she said. "And some people can struggle with this, especially if they have experienced years or even decades of yo-yo dieting and do not have professional support."

Empathy is key in helping people lose weight

All the experts Insider spoke to, including Michaels, said empathy is essential in helping people lose weight, and studies confirm that shaming is an ineffective way to encourage healthy behavior change.

"It's a combination of empathy and empowerment," said Michaels, who has nutrition guidance and fitness programs on her app, The Fitness App.

"The key is simple - we have to eat less, move more, and use common sense with our food choices. If we can do that, our body will function exactly how it's meant to."