The trendy keto diet encourages eating lots of fats, moderate protein, and few carbohydrates. Proponents say it can help with weight loss by forcing the body to burn fat for energy.

The keto trend has become so popular, some parents are encouraging it for their whole families. How-tos for getting kids on the keto diet are popular online, and a cookbook "Keto Kids" was published this summer.

However, nutritionists say can be dangerous to put children and teens on such a restrictive diet, leading to nutritional deficiencies, disordered eating, and long-term health problems.

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Keto, the wildly popular high-fat, low-carb diet, has become a family affair. As it becomes increasingly trendy, fans are now sharing keto with their children.

The search term "keto for kids" hit an all-time high in January of last year, according to Google, and spiked again last August. Keto blogs like "Ditch the Carbs" and "Perfect Keto" provide pros and cons of the keto diet for kids, and social media sites like Reddit are filled with queries from parents on how to get their kids to stick to low-carb eating plans. A new cookbook "Keto Kids" was even published this summer.

But kids and teens have different nutritional needs than adults, and registered dietitians warn that it's generally not recommended for them. Limiting carbs can not only deprive kids of necessary nutrients, it can also increase the risk of eating disorders.

"It can be safe but it's incredibly risky, especially when not monitered by a professional," registered dietitian Rachael Hartley told Insider.

Here's what to know if you're thinking of putting your kids on the keto diet.

Kids' growing bodies and brains need a wide variety of nutrients, including high-carb foods like whole grains and fruits

The idea behind keto is that cutting carbohydrates and increasing the amount of fat you eat can train the body to burn fat for fuel instead of glucose. A transition phase, sometimes known as the "keto flu," can cause fatigue, brain fogginess, and other symptoms as the body tries to adjust.

This is uncomfortable for adults, but can be risky for kids, who need energy provided by carbs to grow.

"Lack of carbohydrates is really concerning for children," Hartley said. "You're depriving the brain of its preferred source of fuel, and that lack could result in fatigue and difficulty concentrating. You can see how that would be challenging for kids trying to do well in school or sports."

Cutting carbs also means limiting healthy food groups like whole grains, fruits, and even some vegetables like potatoes and squash, according to Hartley.

That can deprive children (and teenagers) of important nutrients like B vitamins, folate, potassium, and magnesium. Fiber is also an important nutrient in grains and produce, which is crucial for good digestion and healthy gut bacteria.

If parents are attempting keto to help a child lose weight (which is not recommended), that can backfire, registered dietitian Brigitte Zeitlin said.

"If you're concerned about child or teen obesity, the way to combat that is remove processed foods, sweets, candies, not to remove food groups like whole grains, fruit and veggies," Zeitlin said. "To restrict plant based foods is not the answer to weight loss."

Keto staples like eggs and avocados may not naturally appeal to many picky eaters. Shutterstock

Restrictive diets of any kinds have been shown to put kids and teens at risk of disordered eating

Keto was never intended for general use, according to Zeitlin. It was developed as a last-resort treatment for children with epilepy and other seizure disorders who didn't respond to medications.

Keto can also be also problematic for kids simply because it's so restrictive. The American Academy of Pediatrics cautions against any kind of dieting for children. There's substantial research linking diets with weight gain as well as increased risk of eating disorders, particularly over the long term.

Zeitlin said any weight loss or dietary concerns about children should be addressed with a pediatrician before parents start restricting any food groups.

"When you're teaching children a restrictive diet, you're teaching them food shaming, body shaming, disordered eating, not teaching them a healthy relationship with food," she said.

Instead of diets, the best thing families can do is prepare foods together and include a wide variety of healthy options

Instead of doing keto together, Hartley recommends that families spend more time in the kitchen preparing a wide variety of foods. Parents can model healthy behaviors by eating a variety of foods and teaching kids that there are no "bad" foods, she explained.

If parents do stay on a keto diet, they should always have non-keto food available for their kids, even if that means risking temptation.

"If you don't trust yourself with those foods in the house, if in a moment of weakness, you're going to tear through your kid's snack pack, maybe keto isn't the right plan for you either," Zeitlin said.

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