Insulin resistance, blood glucose levels, and body weight are interconnected, but they are not the same thing. In short, yes, it is possible to lose weight even with insulin resistance, and even moderate weight loss can improve insulin sensitivity. There is no need to “lower insulin” or eliminate carbohydrates: the key is to improve overall metabolic health through a balanced diet, physical activity, and appropriate lifestyle habits.
“When we talk about insulin resistance, the number on the scale is only one part of the picture: what matters is its impact on the overall metabolic profile,” explains Rosa Maria Paragliola, Associate Professor of Endocrinology at the Degree Programme in Medicine and Surgery and the Degree Programme in Human Nutrition Sciences at UniCamillus University. “That is why early intervention is important.”
This guide covers insulin resistance, blood glucose levels to be aware of, symptoms to look out for, and what to eat.
Insulin Resistance, Blood Glucose, and Weight: What Is the Connection?
To understand the relationship between these three factors, it is useful to start by distinguishing between them.
Blood glucose is the concentration of glucose in the blood. Glucose is one of the body’s main sources of energy and comes largely from foods containing carbohydrates.
Insulin is a hormone produced by the pancreas. After a meal, when blood glucose levels rise, the body produces insulin to help glucose enter the cells and regulate energy metabolism.
Body weight, on the other hand, depends on many factors. These include energy balance, meaning the relationship between energy consumed through food and energy expended, as well as diet composition, physical activity, sleep, stress, and individual characteristics, many of which are also genetically determined.
For this reason, it is incorrect to assume that lower blood glucose levels or reduced insulin production automatically lead to weight loss.
Guidance from the Italian National Institute of Health (Istituto Superiore di Sanità, ISS) highlights the importance of an integrated approach to metabolic health, including a balanced diet, physical activity, weight management, and healthy lifestyle habits, including good sleep quality and stress management.
Insulin and Body Weight: Does Insulin Cause Weight Gain?
Saying that “insulin makes you gain weight” is an oversimplification.
After eating, particularly when a meal contains carbohydrates, blood glucose levels rise and the pancreas produces more insulin. This is a normal physiological response that enables the body to process glucose.
Insulin also plays a role in regulating energy stores, but this does not mean that every increase in insulin after a meal automatically leads to an increase in body fat.
Weight gain or loss depends primarily on overall energy balance and numerous individual factors. Diet quality, the amount of food consumed, physical activity, and daily habits also play a role.
Therefore, when trying to lose weight, it is not helpful to focus exclusively on insulin. It is more important to address lifestyle as a whole and develop an eating pattern that supports a sustainable and appropriate energy intake.
“Insulin is an essential hormone for our bodies. The problem is not the normal increase in insulin after a meal, but the possible loss of tissue sensitivity to its action and the metabolic context in which this occurs,” Professor Paragliola continues.
Insulin Resistance: What Is It and Why Does It Develop?
What is insulin resistance? In simple terms, it is a condition in which the body’s cells respond less effectively to insulin.
To compensate for this reduced sensitivity, the pancreas may increase insulin production. This is known as compensatory hyperinsulinaemia.
In the early stages, this mechanism may keep blood glucose levels within the normal range. However, if insulin resistance persists and worsens, the body’s ability to compensate may no longer be sufficient, and blood glucose levels may rise.
Insulin resistance is frequently associated with overweight and, in particular, excess abdominal fat. However, the relationship is complex and should not be interpreted as a simple cause-and-effect relationship.
“In the early stages of insulin resistance, blood glucose levels may still be normal because the pancreas compensates by producing more insulin. This is why ‘normal’ blood glucose levels and ‘metabolic health’ are not necessarily synonymous,” the professor explains. “Insulin resistance can nevertheless be a potentially reversible condition through appropriate lifestyle changes, before more serious consequences develop.”
This does not mean, therefore, that insulin is the sole cause of weight gain or that people with insulin resistance cannot lose weight.
Insulin Resistance and Weight Loss: Is It Possible to Lose Weight?
Yes, it is possible to lose weight even if you have insulin resistance.
The principle underlying weight loss remains a sustainable negative energy balance over time: the energy obtained through food must, overall, be lower than the energy the body expends.
The ADI-AMD-SID intersocietal recommendations on “Nutrition and Diabetes” highlight the importance of reducing calorie intake when necessary, alongside increasing energy expenditure through physical activity and making lifestyle changes.
Furthermore, in people who are overweight or living with obesity, even moderate weight loss can help improve insulin sensitivity and metabolic control.
Weight loss, therefore, is not just about seeing the number on the scale go down. When excess weight is present, losing weight can also have positive effects on glucose regulation.
“The metabolic benefits do not necessarily require substantial weight loss. In people who are overweight or living with obesity, even an initial reduction of 5–7% of body weight, provided it is maintained over time, can significantly improve insulin response and positively affect several metabolic risk factors,” Paragliola explains.
Can You Lose Weight Quickly With Insulin Resistance?
Looking for a way to lose weight quickly is understandable, but there is no single rate of weight loss that is suitable for everyone, and drastic strategies are not necessary to improve metabolic health.
In the presence of insulin resistance, the goal should be gradual, sustainable weight loss that is compatible with individual needs and characteristics.
Extremely restrictive diets or the indiscriminate elimination of entire food groups can be difficult to maintain in the long term. A more effective approach is to progressively improve diet quality, manage portion sizes, increase physical activity, and address lifestyle factors and habits that may affect metabolism.
In other words, losing weight does not necessarily mean losing it as quickly as possible. It means finding a strategy that supports gradual weight reduction and long-term weight maintenance.
High Blood Glucose: Symptoms to Recognise
Hyperglycaemia may not cause symptoms, particularly when the increase in blood glucose is mild or moderate. However, when blood glucose levels are significantly elevated, certain warning signs may appear and should not be ignored.
The main symptoms of high blood glucose, as identified by the Italian National Institute of Health (ISS), include the following:
- Excessive thirst;
- Increased frequency of urination;
- Unexplained and involuntary weight loss.
It is important to emphasise that weight loss in this context is very different from weight loss achieved intentionally through diet and physical activity.
When glucose remains excessively high in the blood and is not used properly by the cells, it may be excreted in the urine. In cases of significant impairment of glucose metabolism, the body may therefore rely more heavily on its energy stores, leading to unintentional and consequently pathological weight loss.
If excessive thirst, frequent urination, and unexplained weight loss occur, it is advisable to consult a doctor and undergo the necessary tests.
Blood Glucose: Normal Levels and Values to Monitor
Knowing the main blood glucose levels can help you understand when a result may require further investigation.
The diagnostic criteria used to assess diabetes and abnormalities in glucose metabolism include:
- Fasting blood glucose ≥126 mg/dL: a value consistent with diabetes;
- Fasting blood glucose between 100 and 125 mg/dL: impaired fasting glucose and an increased risk of developing diabetes;
- 2-hour OGTT blood glucose between 140 and 199 mg/dL: impaired glucose tolerance;
- 2-hour OGTT blood glucose ≥200 mg/dL: a value consistent with diabetes;
- Glycated haemoglobin (HbA1c) ≥6.5%: a value consistent with diabetes.
In all cases, these values must be interpreted by a doctor in the context of the patient’s overall clinical picture.
Oral Glucose Tolerance Test (OGTT): Which Values Indicate an Abnormality?
The oral glucose tolerance test (OGTT) assesses how the body responds after drinking a solution containing 75 grams of glucose.
Blood glucose is also measured two hours after the glucose load.
A 2-hour result:
- Between 140 and 199 mg/dL indicates impaired glucose tolerance;
- Equal to or greater than 200 mg/dL falls within the diagnostic criteria for diabetes.
Here too, the result must be interpreted by a doctor.
Insulin Resistance: Diet and Nutrition
When insulin resistance or abnormal blood glucose levels are present, diet is one of the most effective tools for improving metabolic health.
However, there is no single diet for insulin resistance that is suitable for everyone. The eating plan should be tailored to individual needs, the presence of overweight or obesity, physical activity levels, and clinical conditions.
The recommendations of the Italian Society of Diabetology promote a Mediterranean-style diet, based primarily on:
- Vegetables;
- Legumes;
- Grains, preferably whole grains;
- High-quality protein sources;
- Fish;
- Extra virgin olive oil and other unsaturated fats.
It is also advisable to limit added sugars, sugar-sweetened beverages, and highly refined foods, particularly when they contribute to excessive calorie intake.
The aim is not to eliminate carbohydrates completely, but to choose the quality, quantity, and combination of foods carefully.
“When insulin resistance is present, it is not necessary to eliminate carbohydrates from the diet,” the expert explains. “Instead, it is important to prioritise high-quality carbohydrate sources and fibre-rich foods, pay attention to portion sizes, and include them as part of a balanced diet suited to each individual’s characteristics.”
Low-Glycaemic-Index Diet: Does It Help With Weight Loss?
A low-glycaemic-index diet can be a useful way to improve carbohydrate quality within an eating plan, but it should not become a rigid list of “good” and “bad” foods.
The glycaemic index (GI) measures how quickly a carbohydrate-containing food tends to raise blood glucose levels compared with a reference food.
The general categories are:
- GI ≤55: low;
- GI 56–69: medium;
- GI ≥70: high.
Low-GI foods tend to produce a more gradual rise in blood glucose. However, the glycaemic index alone is not sufficient to assess the effect of an entire meal.
It is also important to consider the amount of carbohydrates consumed, as well as the presence of fibre, protein, and fat. This is why the concept of glycaemic load is also used: it takes into account both the quality and the quantity of carbohydrates.
A low-GI diet can therefore be part of a balanced eating plan, but its value should be assessed within the overall dietary pattern and in relation to the individual’s goals.
Blood Glucose, Insulin Resistance, and Weight Loss: Key Takeaways
The relationship between blood glucose, insulin, insulin resistance, and body weight is real, but it is far more complex than the formula “more sugar equals more fat.”
Insulin is an essential hormone, and its increase after a meal is a normal physiological response. Insulin resistance, on the other hand, means that the body’s cells respond less effectively to insulin and may be associated with overweight and obesity.
When excess weight is present, losing weight can help improve insulin sensitivity and blood glucose control. However, weight loss does not require you to “eliminate” insulin or completely cut carbohydrates out of your diet.
At the same time, very high blood glucose accompanied by excessive thirst, frequent urination, and unintentional weight loss is not a sign of normal weight loss. It may indicate a metabolic disorder that requires medical assessment.
The most effective strategy is therefore to focus on overall metabolic health through a balanced diet, physical activity, weight management, adequate sleep, and stress management.
There is no need to search for a single “perfect” food or the lowest possible blood glucose or insulin level. The goal is to build a sustainable lifestyle that supports a healthy weight and good metabolic control over time.