The GMC's annual report for 2017 - The State of Medical Education and Practice in the UK - says the supply of new doctors into the UK medical workforce 'has not kept pace with changes in demand'.
The UK's dependence on overseas-qualified doctors is rising in some specialties, but the country 'is at risk of becoming a less attractive place for overseas doctors to work', it warns.
Strain on the existing workforce and on doctors training and being trained continues to rise, the report adds.
In general practice, the report says, there was a 3% rise in the number of doctors on the GP register between 2012 and 2017 - below the 4% rise in overall population across the UK, and 'significantly behind' a rise in people aged over 65 that ranged from 11.4% to 13.2% across UK nations between 2011 and 2016.
The report acknowledges efforts to improve the GP workforce through increasing medical school places and GP training places, but warns that new doctors coming through the pipeline will only materialise from 2023.
The depth of the GP workforce shortage varies across the UK. The east of England has the lowest number of GPs per head of population, with just over 0.75 doctors on the GP register per 1,000 people, while south-west England has the highest ratio of GPs to patients, with around 1.1 GPs on the medical register per 1,000 patients.
The report also shows that 17% of GPs faced complaints between 2012 and 2016, with 5.3% investigated and 0.7% warned or sanctioned.
BMA chair Dr Chaand Nagpaul said: 'We welcome the regulator’s recognition that the NHS is in the midst of a workforce crisis.
'Today’s report reflects our own concerns - notably that the number of doctors has failed to keep up with demand, leaving the health service underprepared to meet current demands and manage a growing and ageing population suffering from increasingly complex conditions.
'The report shows that doctors are increasingly choosing to take breaks in training or in some cases leaving the profession all together, often due to heavy workloads, poor morale and burnout. It is vital that we address these issues to ensure medicine is seen to be an attractive and accessible career choice, and the solutions proposed by the GMC are a step in the right direction.'
RCGP chair Professor Helen Stokes-Lampard said: 'This wide-ranging report shines a light on the very real workforce pressures we are facing in general practice and ultimately, makes a loud and clear statement that we need more GPs.
'It is clear we need to be training more doctors here in the UK - and we have welcomed the government’s commitment to increase medical school places. But we also need to ensure that a high proportion of medical students and foundation doctors choose general practice.'
Senior medicolegal adviser at the Medical Protection Society Dr Pallavi Bradshaw said: 'This report shows that the vast majority of GMC investigations are closed without further action, the end result being that over a thousand doctors go through a needless, stressful and slow process each year, while many complainants also end up disappointed with the outcome. While some improvements have been made in this area, the GMC must continue to improve the complaints triage process as a priority to avoid unnecessary investigations.'