In Reply: Drs Ebbeling and Ludwig clarify the nature of the attention and contact provided to participants in the NSB reduction group but not provided to their study's control participants.1 However, while they maintain this was an unlikely confounder, earlier findings documenting beneficial effects of mail and telephone contacts on weight control2 challenge this assertion. Only good experimental design holding therapeutic contact constant across experimental groups can resolve this issue.
Allison DB, Mattes RD. Nutritively Sweetened Beverages and Obesity—Reply. JAMA. 2009;301(21):2209-2211. doi:10.1001/jama.2009.744