Approaches to climate labelling are gaining significant importance in food marketing. Labels that are based on carbon offsets are becoming increasingly popular. However, offsetting-labels have been criticized as misleading and are subject to accusations of greenwashing. The proposal of the EU Green Claims Directive therefore requires companies to substantiate claims. This study employs a consumer survey (n = 2,109) using a between-subjects and within-subjects design to explore how German participants evaluate the climate impact of six food products (ranging from low to very high) through five distinct climate labels: (1) ‘climate-neutral’ (without any declaration), (2) ‘climate-compensated’, (3) ‘climate-neutral and CO2-compensated product’ (declaration according to the proposed EU Green Claims Directive), (4) informative labels indicating the actual climate impact as a numeric carbon footprint (kg CO2eq/kg of food) or (5) as an interpretative traffic light-like label. Except for the numeric indication of the carbon footprint (4) and the traffic light (5), all climate labels significantly skewed perceptions of a food’s climate impact positively, compared to the control group without any label. The effect was sometimes even stronger for highly involved consumers. In contrast, the interpretative traffic light climate label helps to correctly assess the climate impact. In summary, green claims such as ‘climate-neutral’ can be misleading by fostering a false perception of a food’s climate impact, even when the compensatory character is explained or justified close to the claim. This challenges the approach of the draft European Green Claims Directive, which posits that additional information (‘substantiation’) is sufficient to avoid misconceptions.