How Insulin Resistance Affects Weight

Insulin resistance and obesity are closely related conditions, each with rapidly increasing prevalence. Insulin resistance affects about 40% of middle-aged adults in the United States. Insulin resistance is associated with weight gain and can impact metabolism, potentially increasing the risk of developing other metabolic concerns, like type 2 diabetes, cardiovascular disease, hypertension, hyperlipidemia, and non-alcoholic fatty liver disease. 

Addressing insulin resistance and weight gain may benefit from a multidisciplinary approach, including lifestyle modifications focused on nutrition, physical activity, sleep, and stress management. Understanding the close relationships between insulin resistance and weight gain allows us to focus on lifestyle interventions to support both conditions with a personalized approach.

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What Is Insulin Resistance?

Understanding insulin resistance requires knowledge of the physiology of insulin. Insulin is released by the pancreatic beta cells in response to an increase in blood glucose. In healthy individuals, insulin release occurs when carbohydrates are metabolized. When carbohydrates are consumed and metabolized, blood glucose rises, signaling the pancreas to release insulin. Insulin then helps manage blood glucose levels by instructing cells on how to use the glucose - either to shuttle it to various organs to be used for energy or to store the glucose as fat (adipose tissue).

However, insulin resistance occurs when this process is compromised, as a consequence of blood glucose remaining consistently elevated or the pancreas being constantly stimulated to release insulin. Insulin resistance also manifests in cellular receptors that are less responsive to insulin stimulation, limiting glucose uptake into cells and affecting energy availability.

Causes of Insulin Resistance

Various lifestyle factors, genetic factors, and hormonal imbalances can contribute to insulin resistance:

Lifestyle Factors: 

Lifestyle factors play a significant role in the development of insulin resistance.

• Diets high in processed foods, including refined carbohydrates, added sugars, and processed meats, can lead to increased insulin release from the pancreas. This may create a proinflammatory state and increase the risk of insulin resistance. 
• Physical inactivity is a risk factor for developing insulin resistance. 
• Insulin resistance and weight gain are reciprocally related; insulin resistance can contribute to obesity, which then independently increases the risk of insulin resistance.

Genetic Factors: 

In addition to lifestyle factors, genetic predispositions can also increase the risk of insulin resistance. Variations in genes coding for insulin signaling, lipid metabolism, mitochondrial activity, and inflammatory mediators are genetic factors that can increase the risk of insulin resistance.

Examples of genetic markers that may increase the risk for insulin resistance include these:

• PTB1
• LEPR
• RETN
• SLC2A4

Hormonal Imbalances: 

Imbalances of neuroendocrine hormones can significantly affect insulin resistance. Dysregulated glucagon-like peptide-1, glucose-dependent insulinotropic peptide (GIP), ghrelin, peptide YY, and others can influence insulin release from the pancreas. 

Hormone imbalances in conditions like polycystic ovarian syndrome (PCOS) may lead to elevated insulin levels and decreased activity of insulin on organs, further increasing the risk of weight gain and obesity.

How Insulin Resistance Affects Body Weight

Insulin resistance can disrupt the signaling of glucose usage, promoting glucose storage as fat. Reciprocally, excess accumulation of fat (adipose tissue) is a significant risk factor for developing insulin resistance. Adipose tissue (particularly visceral or abdominal fat) secretes pro-inflammatory cytokines and adipokines, which are known to disrupt insulin signaling pathways, thus promoting insulin resistance.

In addition, elevated levels of free fatty acids in obesity may further exacerbate insulin resistance by interfering with insulin action in peripheral tissues. Finally, insulin is a pro-inflammatory hormone, and obesity is a proinflammatory state. Chronic inflammation and obesity are each associated with energy storage rather than energy burn, potentially fueling a continuous cycle of weight gain and metabolic dysfunction.

Research Insights

Current research evidence suggests that insulin resistance can disrupt normal metabolic processes and contribute to weight gain. Increasing levels of circulating insulin, to which cells are resistant, may promote fat storage, specifically visceral fat. Elevated insulin levels can disrupt insulin signaling and promote the storage of excess glucose as fat as opposed to using it for energy. Studies indicate that insulin resistance may also increase hunger and cravings for high-carbohydrate foods. This further contributes to weight gain and increased body fat. As insulin resistance is associated with inflammation, both of these may worsen weight gain and metabolic dysfunction.

Tips For Managing and Preventing Weight Gain

The following tips can be considered to help manage weight gain:

Dietary Strategies

Diet is one of the most significant factors influencing insulin sensitivity. A healthy diet may prioritize whole, natural, nutrient-dense foods, including fiber and healthy fats, while also minimizing the consumption of refined carbohydrates, added sugars, and other processed foods. 

Anti-inflammatory, nutrient-dense foods to emphasize:

• Fruits, like apples, berries, oranges 
• Vegetables, like green leafy vegetables, broccoli, cauliflower, squash, sweet potatoes
• Whole grains, like brown rice, whole wheat pasta, quinoa
• Healthy fats, especially omega-3 fatty acids, like olive oil, avocado oil, avocados, fatty fish
• Lean proteins, like chicken breast, lean pork, turkey breast, egg whites 

Proinflammatory foods to minimize:

• Processed meats, like sausages, cured meats, burgers
• Added sugars, including high fructose corn syrup, candies, cereals, desserts
• Refined carbohydrates, like chips, crackers, cookies, white breads, white pastas
• Trans fats, like baked goods, processed snacks, prepared foods

Low Carbohydrate Diets

Low carbohydrate diets have been shown to support insulin sensitivity, especially in individuals who are overweight or obese. Reducing carbohydrate intake may help manage blood sugar levels, thus decreasing insulin secretion. As insulin levels are lower, insulin sensitivity can improve. 

The added benefit of weight loss from low carbohydrate diets may also enhance sensitivity to insulin. With improved insulin sensitivity, low carbohydrate diets can be effective in helping manage and even support the prevention of type 2 diabetes mellitus. Very low carbohydrate diets (as with the ketogenic diet) present sustainability concerns in the long term, so finding the proper balance of macronutrients through a personalized nutrition plan helps optimize outcomes.

Low Glycemic Diets

A low glycemic index (GI) diet is often recommended to support insulin resistance management. Low-glycemic index foods are digested more slowly, leading to a slower rise in blood sugar and associated insulin levels. This may help maintain more stable blood glucose ranges, reducing the release of insulin. Increasing the intake of high-fiber foods like fruits, vegetables, legumes, and whole grains can help minimize blood sugar spikes, decreasing insulin release and thus promoting insulin sensitivity. 

Physical Activity Strategies

Regular physical activity, including cardiovascular exercise and strength training, is vital in supporting insulin sensitivity and maintaining an optimal weight. Cardiovascular exercise, like fast walking, jogging, running, cycling, and swimming, may enhance insulin sensitivity by increasing glucose uptake and utilization in skeletal muscles. This can help manage blood glucose levels and support insulin resistance management. Cardiovascular exercise is known to help promote a healthy weight by increasing energy expenditure and promoting fat oxidation.

Strength training, including both weight lifting and bodyweight exercise, has also been shown to support insulin sensitivity by increasing muscle mass and increasing glucose uptake into muscles. Strength training is known to help increase and preserve lean body mass, supporting long-term weight management by increasing resting energy expenditure. Combining both cardiovascular exercise and strength training may improve insulin sensitivity, promote weight loss, and help maintain metabolic health.

Sleep

Adequate sleep is crucial to support insulin resistance management by potentially lowering inflammation and enhancing insulin sensitivity. Poor sleep quality may lead to higher cortisol and ghrelin levels, which can predispose to more inflammation, increased appetite, weight gain, and insulin resistance. Prioritizing good quality sleep may promote good metabolic health and help regulate neuroendocrine hormones.

Stress Management

Stress management is an important part of a holistic approach to managing insulin resistance. Controlling stress may help reduce inflammation to support insulin sensitivity. Chronic stress may lead to higher cortisol levels, which can promote inflammation and affect insulin resistance. Utilizing stress-reduction techniques like mindfulness, yoga, deep-breathing exercises, prayer, and time with family and friends has been shown to support inflammation reduction and improve overall metabolic health.

Monitoring and Professional Guidance

Early identification of insulin resistance is important to help delay the onset of type 2 diabetes, cardiovascular disease, and other metabolic concerns. It also allows for lifestyle interventions to be considered first. 

Personalized Management Plans

Using personalized approaches provides effective patient-centered care to improve overall health outcomes. Personalized nutrition plans based on individual health factors should take into account personal preferences and lifestyle factors for best adherence. Specific individualized recommendations should outline the best ratio of macronutrients, timing and composition of meals, and recommended weight goals. 

Monitoring Progress

Tracking improvements in insulin resistance may require the assessment of various biomarkers related to glucose metabolism. 

• Serum insulin levels may be monitored when fasting and after eating. 
• A fasting blood glucose that is performed alongside insulin levels provides an integrated test to get a sense of how insulin levels correspond with serum glucose levels. 
• Hemoglobin A1c (HbA1c) testing measures the average blood glucose levels over the life of the hemoglobin molecule, which is generally about 3 months. HbA1c levels < 5.7% may indicate effective management of insulin resistance.

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Key Takeaways

• Insulin resistance represents metabolic disruptions that may contribute to weight gain.
• Insulin resistance can lead to increased insulin produced by the pancreas, potentially leading to perpetual inflammation, and more glucose stored as fat as a result.
• Increased levels of adipose tissue may promote weight gain.
• Lifestyle factors can help manage insulin resistance and support weight management, including dietary modifications, regular physical activity, adequate sleep, and managing stress.
• Developing personalized management plans may help manage insulin resistance by promoting long-term adherence and aiding in weight maintenance.