An "artificial barrier" helps eaters decide when to stop, says Andrew Geier, lead author of the study published in Health Psychology.

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"John knows what he wants to get done, and he gets it done, " says Philip Geier, the former chairman of Interpublic.

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But the Justice Department, in a brief supporting the plaintiffs, makes the lawyerly argument that Geier applies only to the facts in that case.

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