Sir Peter Jackson, director of epic Middle-earth trilogies "Lord of the Rings" and "Hobbit" has been in his own battle for Middle-tummy. The New Zealander Jackson was obese, then lost weight, and now has gained most all of it back. In 2016, Jackson looks almost as heavy as his LOTR days. The 54-year-old filmmaker's yo-yo weight underscores challenges of maintenance diet. It also highlights how overwork and lack of sleep can sabotage weight loss.

Peter Jackson: work-related weight gain?

In 2005, Jackson wowed the world by losing a stunning 70 pounds.

The ONZ KBNZ (Order of New Zealand Merit) decorated director who had jokingly been said to resemble a hobbit himself began to look more like the lean, trim elf Legolas! By 2016, Jackson has regrettably fallen into obesity again. Weight gain has aged him and he looks 30 years older than his boyish 2009 image. How did this transformed man gain back all the weight he originally lost? There are a couple of probable causes. First, is the danger of exhaustion. Jackson said that on the Lord of the Rings trilogy, he would work 21 hours a day and get a scant 3 hours of sleep. Did you think that work would help weight loss? It should in theory -- if you stay busy, you have no time to eat. Keeping active means keeping fit.

But actually overwork and sleep deprivation can derail a diet quicker than overeating.

Lack of rest and stress derail weight loss

Like Carrie Underwood, Jackson didn't diet to lose weight. He just swapped out the junk food for things like yogurt and muesli. This approach worked to get Chris Pratt the role of Star-Lord on "Guardians." But then Jackson didn't keep up with it.

When you're overworked you don't take time to eat properly. Especially in show biz, it's super-easy to grab canteen food. You eat most of your meals on the run so they have to be convenience (high calorie) foods. You go all day without eating and get so starved by 10 pm that you do a Taco Bell drive-by. You order far more food than you should and wolf it down.

You skimp on sleep and exercise.Also, high stress jobs where you're intensely focused on minute details (like filmmaking or computer work) create problems with eating. And calorie counting gets old, period. Losing weight is one thing -- keeping it off with a sustainable maintenance diet is the harder part.