This is according to new research from Public Health England, which highlights the risk of death and disease linked to weight gain.
If you are in the overweight category – over 25, according to the NHS body mass index (BMI) calculator – you have twice the risk of developing the condition, according to the large-scale study of 2.8 million adults.
To put this in perspective, both the average man and average woman in the UK fall into this category.
The average British male, according to the Office of National Statistics, is 5 foot 9 inches and weighs 12.16 stone. This puts him at a BMI of 27.2 – in the at-risk category.
The same can be said for the “average” British woman, weighing 11 stone and standing at 5ft 3 – a similar BMI of 27.3.
A healthy weight is categorised as between 18.5 to 24.9.
Obesity and disease
For those falling into the “obese” category (see below), the research discovered some worrying trends.
Obese people (a BMI between 30 and 35) have a 70% higher risk or heart failure compared to those of a healthy weight.
Those with a BMI of 35 to 40 have a nine times higher risk of type 2 diabetes. This increases to 23 times for the severely-obese (40-45).
People with a BMI of 40-45 have triple the risk of heart failure, high blood pressure and dyslipidaemia (elevated cholesterol or fats in blood).
A BMI of 40-45 was linked to a 50% higher risk of early death from any cause.
READ MORE: 8 things you need to know about diabetes
"With the number of people living with obesity almost tripling worldwide over the past 30 years (105 million people in 1975 to 650 million in 2016), our findings have serious implications for public health,” said study author, Christiane Haase, of healthcare firm Novo Nordisk which funded the research.
How to calculate your BMI
According to the NHS, your BMI is calculated by using the standard formula of a person's mass in kg divided by the square of their height in metres (kg/m2) and display it to one decimal place.
It can be determined using the NHS Healthy Weight Calculator.
What does your BMI mean?
The NHS divides up BMI results into the following categories.
Less than 18.5 - underweight
18.5 to 24.9 - healthy weight
25 to 29.9 - overweight
30 to 39.9 - obese (split into two categories for the new study)
40 and over - very obese (also known as morbidly obese)