Research suggests that for every three inches taller a man is, he will earn roughly £1,500 more per year. Meanwhile among women, for every extra stone they weigh it costs them approximately £1,500 per year.
Previous research suggested that the difference in pay - and, indeed, in career opportunities - could be due to worse education opportunities or poor nutrition in childhood and early adulthood.
But a new study suggests that "obsession with body image" could also be to blame, the Press Association reports.
Researchers from the University of Exeter studied data from almost 120,000 people aged between 40 and 70.
They measured participants' height and weight and then looked at 400 genetic variants associated with height and 70 variants associated with body mass index (BMI).
They then compared the information with livelihood and income of the participants.
The results showed that shorter height led to lower levels of education, lower job status and less income - particularly in men.
Meanwhile higher BMI led to lower income and greater deprivation in women.
Co-author Professor Tim Frayling, from the University of Exeter Medical School, said: "This is the best available evidence to indicate that your height or weight can directly influence your earnings and other socio-economic factors throughout your life.
"This won't apply in every case. Many shorter men and overweight women are very successful, but science must now ask why we are seeing this pattern.
"Is this down to factors such as low self-esteem or depression, or is it more to do with discrimination?
"In a world where we are obsessed with body image, are employers biased? That would be bad both for the individuals involved and for society."
Prof Frayling gave examples of how a difference in height and weight might affect income.
He said: "If you could take the same woman - same intellect, same CV, same background - and send her through life a stone heavier, she would be about £1,500 per year worse off.
"And if you took the same man - say a 5ft 10in man and make him 5ft 7in - and sent him through life, he would be about £1,500 worse off per year."
Dr Jessica Tyrrell, lead author of the study, added: "The genetic analysis we used is the best possible method to test this link outside of randomly altering people's height and weight for a study, which is obviously impossible.
"Because we used genetics and 120,000 people, this is the strongest evidence to date that there's something about being shorter as a man and having a higher BMI as a woman that leads to being less well-off financially."
The study was published in the British Medical Journal.