Al Roker is once again defending the keto diet.

The “Today” co-host hit back at a dietitian who criticized him for being on the ketogenic diet, which is a very low-carb, high-fat plan that’s been growing in popularity among celebrities.

“Sad to see another famous person falling for a fad diet,” tweeted Heidi Wells, who describes herself as a registered dietitian in her Twitter bio.

JILLIAN MICHAELS CALLS OUT ANDY COHEN, AL ROKER OVER KETO DIET FEUD: 'WHY DON'T WE BEHAVE LIKE ADULTS'

Wells on Thursday was responding to Roker’s Jan. 22 tweet showing his keto-diet dinner of steak fajitas without the tortilla.

Roker replied on Thursday by tweeting: “Heidi, there are so many sadder things in the world. Have a great day.”

This isn’t the first time Roker has defended the diet, which he began last September. The 64-year-old called out Jillian Michaels last month after the celebrity fitness trainer called the keto diet a “bad plan for a million reasons.”

“I don’t understand. Like, why would anyone think this is a good idea,” the 44-year-old trainer said in a Women’s Health video. “‘You know what we need to do? All fat and animal protein! Ding, ding, ding!’ No! Bad plan. For a million reasons.”

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Michaels said the diet doesn’t give the body the important nutrients it needs to promote a healthy lifestyle.

Roker, however, disagreed with her statements and claimed Michaels promoted a slew of “bad ideas.”

“So @JillianMichaels says #Keto is a bad idea. This from a woman who promoted on camera bullying, deprivation, manipulation and more weekly in the name of weight loss. Now those sound like bad ideas,” Roker tweeted on Jan. 10.

He later explained on “Today” that the diet has helped him improve his cholesterol and blood pressure, adding that “what works for you, works for you.”

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“There’s science on both sides that says it’s not a great idea and science that says it is a good idea,” Roker said.

Michaels responded to Roker’s comment by challenging him to a “civil intelligent debate” about the keto diet. The “Today” co-host declined.