Written by: Rebekah B.
Reviewed by: Emily J., MSc RD
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Counting calories and not seeing results? Learn how the vicious cycle between insulin resistance and fat storage may be preventing you from managing a healthy weight.
If you’ve been struggling to lose weight despite dieting and exercising, insulin resistance might be to blame. According to a recent study, 4 in 10 young American adults without diabetes have insulin resistance, which has been strongly associated with adult weight gain [1, 2]. As a condition that impacts millions of non-diabetic Americans each year, insulin resistance (or impaired insulin sensitivity) can lead to weight gain as well as other more serious side effects in the long term.
Insulin resistance occurs when the cells in your body stop responding properly to insulin, a hormone in your pancreas that regulates blood glucose levels.
Normally, the food you eat is converted into glucose, (your body’s preferred energy source), which enters your bloodstream and lets the pancreas know that it’s time to release insulin. But when too much blood sugar enters the bloodstream, the pancreas has to pump out larger-than-anticipated amounts of insulin. Eventually, the cells become desensitized to this excess amount of insulin and stop responding properly, resulting in higher-than-normal blood glucose levels.
Anyone can develop insulin resistance, but lack of physical activity, large waist circumference, and high total fat mass all appear to be contributing factors [3, 1]. Another contributing factor, and perhaps the most impactful, is diet — specifically, a diet high in processed foods, added sugar, refined carbohydrates, and low-quality fat has been strongly associated with the development of insulin resistance .
Some of the most common side effects of insulin resistance include weight gain, difficulty losing weight, blood sugar spikes after eating, extreme hunger or thirst, and tiredness. However, most people don’t experience symptoms at all. Over time, insulin resistance can lead to prediabetes and Type 2 Diabetes, as well as an increased risk of adverse cardiovascular events and all-cause mortality .
Insulin resistance can lead to weight gain, and vice versa, in a positively reinforcing loop. One study of 6,671 men and women found that adult weight gain was associated with more adipose tissue (excess weight that develops around the center of the body) and triglycerides in your liver in middle age, both of which contribute to insulin resistance [5, 6].
But how does this all work?
Both your pancreas and liver play a crucial role in regulating blood sugar levels. Under normal circumstances, when your body’s insulin sensitivity isn’t impaired, your pancreas releases insulin after a meal, which unlocks your cells so they can take in the glucose from your bloodstream and convert it into energy.
At the same time, increased insulin levels also signal the liver to store excess glucose to use as energy later (in the form of glycogen). Any excess glucose is stored as fat . When you’re sleeping or not eating and your body needs to produce energy, your liver will release glucose into your blood for your cells to use .
That all changes when you have insulin resistance: your cells don’t respond properly to insulin, leading to elevated glucose (and insulin) levels in the blood — which promote fat storage in your liver. When your liver begins to accumulate extra fat, it becomes increasingly less sensitive to insulin and pumps additional glucose into your blood when it shouldn’t, triggering your pancreas to release even more insulin to bring those glucose levels back down . These high insulin levels lead to increased fat storage, starting the cycle over again.
If you’re experiencing this self-perpetuating cycle of weight gain/higher insulin levels, it may become harder and harder for you to manage a healthy weight. In a 2022 study, researchers performed two trials where young-to-middle-age participants consumed a calorie-restricted diet with either low or moderate carbohydrates — with the goal of 10-14% weight loss within 10 weeks or 12-18% weight loss within 14 weeks, respectively . They learned that subjects who were more insulin resistant tended to lose less fat mass and more muscle mass than participants who were not insulin resistant.
This isn’t to say that you can’t lose weight effectively if you have insulin resistance, but it means that you have to address the root of the problem: balancing your blood glucose levels and lowering circulating insulin levels. When you shift your focus like this and make resolving insulin resistance your objective, losing weight not only becomes easier but is a natural side effect of the process.
The good news is that insulin resistance is reversible. If you think you may have insulin resistance, you can talk with your doctor and get a blood test (typically a fasting plasma glucose test, oral glucose tolerance test, or hemoglobin A1C test) to check your blood sugar levels. You can also get an “insulin in blood” test, which measures the amount of insulin in your blood, though this isn’t a typical test that your doctor orders in blood panels since there is a lack of consensus about normal insulin levels.
Once you know for sure whether you have insulin resistance (or are at an increased risk for it), you can take the needed steps to get it under control.
Insulin resistance is a two-part problem: too much glucose in your blood and a lack of insulin sensitivity. In the same way that both diet and non-diet factors can lead to insulin resistance, reversing the condition involves making shifts across your lifestyle, including diet and nutrition, exercise, sleep, and stress management.
One of the most simple and effective ways to stabilize your glucose levels and reverse insulin resistance is to change your diet. This means opting for whole fruits and vegetables instead of refined carbohydrates such as processed bread and sugar, which tend to have a high glycemic index that triggers glucose spikes. But it also includes being more thoughtful about meal timing and food order. For instance, eating a fiber-rich salad before consuming carbohydrates can help minimize a glucose spike, and experimenting with time-restricted eating patterns can help you better align your meal schedule with your circadian rhythm (your body’s internal clock) and is linked with weight loss.
Exercise — particularly a combination of resistance training and aerobic exercise — has been linked to improved insulin sensitivity. A review of 11 studies found a connection between increased physical activity levels and lower chances of developing insulin resistance . Another study found that insulin sensitivity increased for at least 16 hours in both healthy subjects and those with Type 2 Diabetes after exercise . Ultimately, all exercise, when done consistently, is a key tool in reversing insulin resistance — choose the type of workout and the time of day that’s easiest for you to stick to.
Cortisol, the stress hormone, is critical to survival — but chronic stress can interfere with the role that insulin plays in your body. That’s because the two hormones are antagonistic: cortisol temporarily decreases insulin sensitivity and increases glucose production in the liver so your body has a readily available source of quick energy. When your cortisol levels are consistently high, your blood sugar levels stay elevated as well. One study of 766 workers in China found that chronic stress was “associated with insulin resistance and may contribute to the development of insulin resistance” . If you’re not sure how to reduce stress, you might want to incorporate sauna sessions or yoga into your routine — one 16-person study found that yoga, mindfulness, and a mobile mindfulness application helped participants manage stress levels .
Consistently poor sleep — both sleep deprivation and an irregular sleep schedule — can take a significant toll on your insulin sensitivity. One study found that not getting enough sleep for just one night induced insulin resistance in healthy subjects . Fortunately, catching up on rest can reverse the effects of poor sleep on insulin resistance. Take steps to improve your sleep hygiene by going to bed at the same time each night, reducing blue light exposure in the evening, avoiding caffeine after 2 p.m., and making your bedroom as dark and quiet as possible.
Insulin resistance can be scary. But like with anything else in life, knowledge is power. Here’s what to keep in mind about insulin resistance: