OKLAHOMA CITY (KOKH) — Almost a month into 2019, and a lot of people are still hanging on to their New Year's diet resolution.
But, experts warn that some diets can actually be dangerous if they're not the right fit.
One popular diet has been keto, or the ketogenic diet, a quick and effective way to lose weight.
If it's working the right way, your body starts to burn off fat instead of carbohydrates for energy.
The diet includes eating a large amount of fat, meat, cheese, dairy, butter and oils.
"The ketogenic diet, if you do it the correct way, 70 percent of your caloric intake is fat, and then I believe 25 percent is protein and five percent or less in carbohydrates," said Erin Martin, a dietitian at Life Nutrition in Oklahoma City. "So, it's extremely high in fat."
Martin has put some of her clients on keto, and has had success, but she warns others to be careful.
"Anyone who is an athlete, or who is extremely active or has an active job," Martin said. "The ketogenic diet has been shown to decrease athletic performance, just because the body runs really well on glycogen, which is carbohydrates."
Martin says, when you're eating that much fat and protein, it's possible to have problems with your liver and kidneys.
Those choosing to go on the diet should meet with a doctor or dietitian first to make sure it's the right fit.
"I do have a couple of clients where it works really well," Martin said. "These are clients who are significantly obese, or morbidly obese, and they are very sedentary, and they don't like to cook."
For some people, Martin says keto can help with diabetes by controlling your glucose or blood sugar levels.
Some of Martin's clients on the keto diet have had what's called the 'keto flu,' with symptoms like being light-headed, having aches and nausea.
Eating that much fat can also cause constipation.
Dietitians say drastically changing your diet can sometimes have a negative affect on your metabolism, and can make it harder to lose weight in the future.