Chipotle Mexican Grill has built its fast-casual burrito dominance largely on consistency and size. It entertains and attracts customers with advertising phrases like “Burrito as big as your head” and “Burrito or dumbbell?” But recent controversy over its portion sizes has left even loyal diners dishing out outrage, and its chief executive responded this week with a plan to ensure consistency.

Amid a storm of customer complaints on social media, accusing the chain of serving smaller portions in their burritos and burrito bowls, Chipotle’s chief executive, Brian Niccol, firmly denied that the company’s portion policies had changed.

“First, there was never a directive to provide less to our customers,” he said during an earnings call Wednesday. “Generous portion is a core brand equity of Chipotle. It always has been, and it always will be.”

Still, Mr. Niccol said the complaints had led him to re-examine Chipotle’s practices across its operation.

“To be more consistent across all 3,500 restaurants, we have focused in on those with outlier portion scores based on consumer surveys,” he said. “We are re-emphasizing training and coaching around ensuring we are consistently making bowls and burritos correctly.”

The suspicions about shrinking burritos and bowls at the beloved budget-friendly restaurant spread widely after a May TikTok video. In the video, Keith Lee, a food critic on the platform, expressed shock at the small portions, asking: “Where’s the chicken at?”