While 94 per cent of the subjects surveyed were making excuses for not exercising, 51 per cent made excuses for not eating more healthily.
Such responses came despite 91 per cent of respondents agreeing that they needed to improve their fitness, and 80 per cent conceding that they needed to mend their eating habits.
Tiredness, a guest's visit, and poor weather were the most popular excuses among respondents.
"Everyone knows the importance and benefits a healthy lifestyle can bring and that they should exercise and eat well - but a startling number of Australians just aren't doing it, and it comes back to the same old excuses," news.com.au quoted dietitian Kate Di Prima as saying.
She said that, with obesity rates more than doubling over the past 20 years, time was running out to curb "this serious epidemic".
The survey also brought to the fore the fact that 40 per cent of people were complete ignoramus as to from where to start or what to do to achieve a healthy lifestyle.
"The key to tackling the obesity problems in Australian society today is educating the large amount of people who may not understand how their everyday eating habits impact upon their health," Di Prima said.