Reminds me of the occasion when I flew a 737-200 from Tontouta airport in New Caledonia, to Wallis Island just west of Samoa. We had a full flight with a take off weight (so we thought) of 53 tonnes (max structural). At cruise altitude of 31,000 ft we repeatedly lost 10-15 knots IAS and needed much higher thrust than was in the tables in order to hold Mach 0.73.
Wallis islanders are big people like the Tongans (they were people eaters back in the bad old days in the South Pacific), and the manifest given to us by the UTA agents had males at 77 kgs and females 67 kgs standard weights. After a while we twigged that the documented ZFW was a long way out.
On arrival at Wallis we arranged for everyone to step on a set of scales as they left the aircraft. The first huge lady almost broke the scales at 140 kgs plus 30 kgs hand luggage. There followed a couple of hefty chaps each around 135 kgs plus 25 kgs plus of hand baggage. There was hardly anyone less than 100 kgs in the whole crowd and the hand baggage didn't help.
After all the weighing was completed, we calculated that the ZFW on departure at Tontouta was over 1.6 tonnes heavier than documented. Needless to say for future island flights we demanded each passenger and hand baggage be weighed individually