United's Lukaku weighed down after muscling up

Soccer Football - Premier League - Manchester United v Fulham - Old Trafford, Manchester, Britain - December 8, 2018 Manchester United's Romelu Lukaku after the match REUTERS/Phil Noble

(Reuters) - Manchester United striker Romelu Lukaku has attributed his sluggish start to the season to a more muscled physique and said he had been staying out of the gym in a bid to improve his form.

The 25-year-old was United's top scorer with 27 goals in all competitions last term and helped Belgium reach the World Cup semi-finals in Russia, but he has scored six times in 20 club appearances.