Does being overweight cause diabetes?

Overweight and obesity are defined as an excessive or abnormal buildup of fat that can seriously harm one's health, primarily by increasing the chance of developing other chronic diseases like diabetes and heart disease. Body mass index (BMI) is a simple index of weight concerning height commonly used to categorize adult overweight and obesity in adults. It is determined by dividing the individual's weight in kilograms by the square of their height in meters (kg/m2).

For adults, according to WHO, overweight and obese are as follows:

• Being overweight is defined as having a BMI of 25 or higher, and
• Obesity is defined as a BMI greater than or equal to 30.
• Due to its universal applicability to adults of all sexes and ages, BMI serves as the most useful population-level indicator of overweight and obesity. However, because it might not equate to the same level of fatness in various people, it should only be used as a general reference.

For children, age must be considered when defining overweight and obesity.

Children under five years of age

• overweight is weight-for-height exceeds two standard deviations above the WHO Child Growth Standards median; and
• obesity is weight-for-height greater than three standard deviations above the WHO Child Growth Standards median.

Children aged between 5–19 years

• overweight is BMI-for-age greater than one standard deviation above the WHO Growth Reference median; and
• obesity is greater than two standard deviations above the WHO Growth Reference median.

Diabetes is a long-term (chronic) illness that affects how your body converts food into energy. With this condition, your body either can't produce enough insulin or can't utilize it as well as it should. Too much blood sugar remains in your bloodstream when insufficient insulin or cells cease reacting to insulin.

Being overweight, obese, and diabetes

Even though we have been using the terms "obesity" and "overweight" interchangeably, their medical definitions differ slightly.

Obesity is a condition where a person has accumulated so much body fat that it may be detrimental to their health. In contrast, being overweight is when the weight may be caused by muscle, bone, fat, or bodily water. If you consider the fats that make up your weight, "obesity" often refers to having significantly more body fat than "overweight."

Nonetheless, being overweight is already a concerning condition since if you consume too much fat, you could become obese. Unhealthy lifestyle patterns, such as not getting enough exercise and consuming foods and beverages high in calories but low in nutrients, can increase your risk of being obese, which increases your risk of developing other severe disorders like diabetes. Type 2 diabetes and excessive fat accumulation have a high correlation.

How do obesity and being overweight relate to diabetes?

It is common knowledge that people who are overweight or obese are more likely to develop type 2 diabetes, especially if they have extra weight around their stomachs (abdomen).

• Inflammatory response

According to studies, fat cells in the abdomen release "pro-inflammatory" substances. Obesity that is particularly high-risk and is characterized by excess abdominal fat (i.e., a big waistline) is referred to as central or abdominal obesity. Inflammation caused by obesity is often low-level but chronic, and a study from 2019 shows that inflammation contributes to the onset of diabetes. By interfering with the function of insulin-responsive cells and their capacity to respond to insulin, this situation might make the body less sensitive to the insulin it generates. Insulin resistance is a defining feature of type 2 diabetes.

Although the exact mechanism is still unclear to scientists, inflammation associated with obesity has a role in insulin resistance. This happens when the body has problems using or producing insulin, making it difficult to quickly absorb glucose from the blood, causing blood sugar levels to rise.

Insulin is a hormone that controls the flow of blood glucose, or sugar, into the cells, which use it as energy. Too much glucose builds up in the blood when sugar cannot enter cells, making it unavailable for the body to use as energy.

Due to insulin resistance, the pancreas that produces the hormone needs to work harder to create enough of it to sustain blood sugar levels due to insulin resistance. Type 2 diabetes can arise because of the pancreas' gradual inability to keep up and loss of insulin-producing capacity.

• Disruption in fat metabolism

The body's metabolism is assumed to change due to obesity because fat tissue (also known as adipose tissue) releases fat molecules into the blood, influencing insulin-responsive cells and diminishing insulin sensitivity.

According to a different hypothesis by researchers, obesity triggers prediabetes, a metabolic disorder that almost invariably progresses to type 2 diabetes.

Does diabetes develop in everyone who is overweight or obese?

Compared to people who are at a healthy weight, those who are obese are around six times more likely to develop Type 2 diabetes. However, diabetes may not always follow fat. There may also be additional considerations, such as:

• Family history
• Diet
• Exercise
• Stress
• Gut condition

According to Dr. Waddadar, some obese persons may be able to manufacture more insulin without stressing their pancreas. Others may have impaired insulin production, increasing the likelihood that obesity may progress to diabetes.

Effects of weight loss on obesity and diabetes

Losing weight can have a significant therapeutic impact on type 2 diabetes, metabolic function, and diabetes comorbidities.

To induce the pancreas to create enough insulin when you have diabetes, you might start with one medicine, according to Dr. Waddadar. However, you will require two or more diabetes medications if not already. However, if you reduce weight, you could only need one drug or possibly stop taking them altogether.

The first step in treating diabetes, according to Dr. Waddadar, is to achieve and maintain a healthy weight while adhering to a low-carbohydrate diet. Even a slight reduction in body weight—5% to 10%—can make a big difference in Type 2 diabetes. 

It can be challenging to alter your diet and exercise to lose weight. However, the effort is worthwhile to prevent diabetes-related severe problems like heart disease, kidney failure, and nerve damage.