From the graph plotted between Mass Number and Binding Energy per Nucleon, we infer the BE/A is stable for mass numbers between 20 and 60 (approximately) and decreases for A>60. Similarly the BE/A is very less for lighter nuclei, say, Helium. Nuclear forces are short range forces. So it is understandable for decrease in BE for heavier nuclei. But, I can't understand why BE is less for lighter nuclei, because there is only a few nucleons and being short range forces, nuclear forces should be predominant. But how BE is less for lighter nuclei which have a very few nucleon?