Insulin Resistance & Weight Loss: Why Kilos Stay
Sometimes you eat less, move more, and the scale barely budges. One possible reason: insulin resistance. High insulin levels can keep the body in storage mode. How to recognise this and which directions may genuinely help.
When someone comes to me and says, „I do everything right and still do not lose weight," I rarely hear a lazy excuse. I hear a body whose signals have gotten tangled. Weight is a hormonal signal, not a pure arithmetic problem. The calorie balance is physically true. But it does not explain what steers hunger, satiety and storage. One central conductor is insulin. With insulin resistance, its level stays chronically high, and high insulin keeps the body in storage mode. In this text I show you what insulin resistance is, how to recognise it, how it develops and which levers may keep blood sugar stable and favourably influence your insulin sensitivity.
This spoke looks at the weight topic in general. It goes through: what insulin resistance actually is, which symptoms and signs exist, how to recognise it and estimate it with the HOMA index, why it can slow weight loss, how visceral fat and silent inflammation sustain it, and which directions the evidence supports. The sex-hormone deep dive sits deliberately elsewhere: for women in the article on insulin resistance and hormones, for men in the article on obesity, insulin resistance and testosterone.
What insulin resistance actually is
Picture insulin as a key. After eating, blood sugar rises. Insulin is the key that opens the cell doors so the sugar can move in. With insulin resistance, the locks have gone blunt. The cells respond less well to the signal. The body does what anyone would do: it turns up the volume. It releases more insulin to achieve the same effect. This creates a chronically elevated insulin level, hyperinsulinemia.
The catch: insulin is not only the sugar key. It is also the body's most important storage hormone. Insulin tells the fat cells to store, and it slows the breakdown of fat. As long as a lot of insulin is around, the body stays in storage mode. This is where the connection to weight loss begins.
Why high insulin switches to storage
Mechanism review Joseph Janssen described in 2021 in the International Journal of Molecular Sciences how chronically elevated insulin shifts the balance between insulin and growth hormone, namely towards storage. The consequence, according to the review: more fat build-up, slowed fat breakdown and a tendency towards lower energy expenditure. For you this means: a high insulin level can make fat breakdown harder, independent of your good will. To be honest: whether the hyperinsulinemia precedes the insulin resistance or the other way round is not yet scientifically settled. The review takes the view that high insulin plays a driving role early on.
Janssen JAMJL. Int J Mol Sci. 2021;22(15):7797. doi:10.3390/ijms22157797 · PMID: 34360563
The most common narrative goes: „Whoever does not lose weight eats too much or is too lazy." The insulin perspective turns that around. Your willpower is not weak. Your body can be stuck in a hormonal state that is programmed to store. That is not a free pass, but it is a fairer starting point. You then work not against your own body, but on its signals.
Recognising insulin resistance: symptoms and signs
The tricky part: insulin resistance causes no loud symptoms for a long time. It is a quiet development, often over years. Still there are hints that many people with insulin resistance know. None of them proves anything alone. Together they form a pattern that can make a check-up sensible.
Growing waistline
Weight gain especially around the midsection, even if arms and legs stay slim. Belly fat and insulin resistance are closely linked.
Cravings for sweets
A pull towards fast carbohydrates, often in the afternoon or evening, sometimes with a sense of never feeling truly full.
Tiredness after eating
The familiar slump after carbohydrate-heavy meals, often followed by an energy dip and the next wave of hunger.
Weight loss is hard
Despite honest effort the scale barely moves, or the kilos come back quickly.
Dark skin patches
Velvety dark discolourations in skin folds, on the neck or in the armpits (acanthosis nigricans) can be a sign.
Fluctuating energy
An up and down of concentration and drive through the day that often follows blood sugar.
Insulin resistance cannot be reliably identified by feeling, only through medical testing. This includes fasting blood sugar, fasting insulin and the HOMA index calculated from them. Waist circumference, triglycerides and long-term blood sugar (HbA1c) also feed into the picture.
The HOMA index: one number that says a lot
The HOMA index (Homeostasis Model Assessment of Insulin Resistance, HOMA-IR for short) is a simple calculated value that estimates insulin resistance. It combines your fasting blood sugar with your fasting insulin. The idea behind it is elegant: if your blood sugar is normal but your body already needs a lot of insulin for it, the locks are already working harder. The HOMA index makes this hidden effort visible, often years before the blood sugar itself becomes noticeable.
„My fasting blood sugar is normal, so everything is fine." That can be deceptive. Blood sugar stays normal for a long time because the body keeps it normal with more and more insulin. Only when this compensation is no longer enough does the sugar rise. A normal blood sugar with high insulin is therefore not a free pass, but rather an early warning sign that is often overlooked.
To be clear: the HOMA index is an approximation, not a perfect test. The thresholds vary by laboratory and situation, and interpretation belongs in medical hands. It is a good compass, not a map. In research it is often used as a marker, for example in the studies by Silver and Sun cited below.
Why insulin resistance can slow weight loss
Now it gets concrete. Why do the kilos stay? Three threads run together. First, storage mode: high insulin promotes fat storage and slows fat breakdown. Second, hunger: fluctuating blood sugar and insulin peaks drive cravings, especially for fast carbohydrates. Third, the silent inflammation that emanates from belly fat and further sustains insulin resistance. More on that third thread in a moment.
Insulin decides whether fat is built or broken down
Mechanism review Lixia Gan and colleagues summarised in 2015 in Frontiers of Medicine how insulin resistance in central obesity drives fat storage. When insulin action is disturbed, the balance between fat build-up and fat breakdown goes off, and the liver starts to build more fat itself. For you this means: insulin is the conductor that determines which direction your metabolism plays. If it is stuck on storage, weight loss is harder, but not impossible.
Gan L, Xiang W, Xie B, Yu L. Front Med. 2015;9(3):275-287. doi:10.1007/s11684-015-0410-2 · PMID: 26290284
At this point honesty matters. The calorie balance is not wrong. Conservation of energy holds. But „eat less, move more" falls short, because it ignores how hard sticking with it becomes when insulin and blood sugar work against you. Chronic, harsh calorie restriction can also fuel cravings and the yo-yo effect. It is often more sensible to first improve the hormonal starting position. Then the rest becomes easier.
The invisible brake: visceral fat and silent inflammation
Not all fat is the same. The fat under the skin on hips and thighs is relatively harmless. The visceral fat that sits deep in the abdomen around the organs is something else. It is not a passive store. It is an active organ that sends out messengers, and many of them are pro-inflammatory.
Belly fat sends inflammatory signals
Mechanism review Tatsuo Kawai and colleagues described in 2020 in the American Journal of Physiology how fat tissue in overweight enters a state of chronic, low-grade inflammation. Overloaded fat cells and infiltrating immune cells produce inflammatory substances that are mechanistically linked to insulin resistance. For you this means: belly fat and insulin resistance keep each other alive. The fat sustains the inflammation, the inflammation sustains the insulin resistance, and that in turn favours new belly fat.
Kawai T, Autieri MV, Scalia R. Am J Physiol Cell Physiol. 2020;320(3):C375-C391. doi:10.1152/ajpcell.00379.2020 · PMID: 33356944
This is why waist circumference often says more than the pure value on the scale. Sandra Milić and colleagues emphasised in 2014 in the World Journal of Gastroenterology that fat distribution influences insulin resistance more strongly than BMI alone. So anyone who loses weight around the belly is working not just on a number, but on an inflammatory, insulin-disrupting depot.
The fight against excess weight is often waged as a fight against the scale. The metabolic view shifts the target. It is less about the kilo itself and more about the visceral fat and the silent inflammation behind it. A few centimetres less around the belly can move more hormonally than the same weight loss anywhere else.
How insulin resistance develops
Insulin resistance does not fall from the sky. It is usually the result of several factors working together over time. From the perspective of Clinical Psychoneuroimmunology, we look at the picture through several lenses, rather than searching for a single culprit.
Metabolism and nutrition
Many heavily processed foods, sugar and white flour drive repeated insulin peaks. Over years this can make the cells less sensitive. The quality of carbohydrates plays a central role, not just the quantity.
Inactivity and muscle
Muscles are the body's largest consumer of sugar. Little movement and little muscle mass mean more sugar stays in the blood and more insulin is needed. Muscle is insulin sensitivity in action.
Immune system and inflammation
Silent inflammation from visceral fat, from the gut or from processed food can disturb the insulin signals. Inflammation and insulin resistance reinforce each other.
Nervous system, sleep and stress
Sleep deprivation can worsen insulin sensitivity in the short term. Chronic stress raises blood sugar through cortisol and favours belly fat. The mind eats along, and the metabolism listens.
And now you know why there is rarely a single cause. This is exactly why a single trick rarely lasts. What often carries is pulling on several of these threads at the same time.
What can help: exercise and muscle
If I had to highlight one lever that is often underestimated, it is muscle. Exercise, especially resistance training, can favourably influence insulin sensitivity, and partly independent of weight loss.
Resistance training improves insulin sensitivity, even without losing weight
RCT, n=9 Javier Ibáñez and colleagues showed something remarkable in 2005 in Diabetes Care. Older men with type 2 diabetes trained twice a week with weights for 16 weeks, without an accompanying weight-loss diet. Result: visceral belly fat fell by around 10 percent, insulin sensitivity rose by about 46 percent, and that with unchanged body weight. For you this means: even if the scale stands still, building muscle can clearly improve your insulin situation. The study is small, but the effect is clear and mechanistically well understood.
Ibáñez J, Izquierdo M, Argüelles I, et al. Diabetes Care. 2005;28(3):662-667. doi:10.2337/diacare.28.3.662 · PMID: 15735205
Combined training lowers blood sugar and inflammation
Meta-analysis, k=20, n=1192 Sameer Al-Mhanna and colleagues pooled twenty studies with 1192 participants in 2024 in PeerJ. In people with type 2 diabetes and overweight, combined aerobic and resistance training improved long-term blood sugar (HbA1c), blood pressure and several inflammatory markers such as CRP, TNF-alpha and IL-6. For you this means: exercise works not only through calories, but reaches directly into the insulin and inflammation situation. A second meta-analysis by Zhang 2023 in Archives of Physical Medicine reached similar results and gave as a guide at least 135 minutes of exercise per week, part of it resistance training.
Al-Mhanna SB, Batrakoulis A, Wan Ghazali WS, et al. PeerJ. 2024;12:e17525. doi:10.7717/peerj.17525 · PMID: 38887616
What can help: carbohydrate quality and weight loss
With food it is worth looking away from pure quantity, towards quality. Above all, the type and amount of carbohydrates influence how strongly your blood sugar and your insulin swing after a meal.
Fewer carbohydrates, more effect on weight
RCT, n=302 Jia Sun and colleagues compared different strategies in 2023 in BMC Medicine, in a multicenter RCT with 302 participants. Reducing carbohydrates without a fixed calorie cap lowered BMI more than pure calorie restriction, and the combination was most effective. Honesty requires: the HOMA index did not differ significantly between the groups over the twelve weeks. Weight, waist and blood fats therefore often improve faster than the pure insulin value. For you this means: what you eat can be as important as how much, and patience is part of it.
Sun J, Ruan Y, Xu N, et al. BMC Med. 2023;21(1):192. doi:10.1186/s12916-023-02869-9 · PMID: 37226271
Weight loss lowers silent inflammation
RCT, n=1759 L. Maria Belalcazar and colleagues evaluated data from the large Look AHEAD study in 2010 in Diabetes Care. One year of intensive lifestyle intervention in people with type 2 diabetes lowered the inflammatory marker hs-CRP by about 44 percent, compared with around 17 percent in the control group. The drivers were less body fat and better glucose control. In addition, Heidi Silver found in 2023 in Diabetes, Obesity and Metabolism that calorie restriction reduced visceral fat by almost 10 percent, and that leaving out simple carbohydrates in particular went along with a better insulin situation. For you this means: losing weight around the belly can release the inflammatory brake.
Belalcazar LM, Reboussin DM, Haffner SM, et al. Diabetes Care. 2010;33(11):2297-2303. doi:10.2337/dc10-0728 · PMID: 20682679
Backed by RCTs is therefore: building muscle can improve insulin sensitivity, carbohydrate quality can lower weight and blood fats, and weight loss can clearly reduce silent inflammation. What remains open: how quickly and how strongly the HOMA index improves under short interventions varies between studies. I describe directions here, not guarantees.
Keeping blood sugar stable: the connecting principle
Above all runs one simple thread: aim for the most stable blood sugar possible. Every large blood sugar spike demands an insulin response. The calmer the curve, the less insulin, the less storage signal. In practice this does not mean going without, but combining more wisely: protein and fibre first, favour unprocessed foods, avoid sugary drinks, and take a short walk after eating. How strongly your personal blood sugar reacts to individual meals can be made visible by a sensor. That is a powerful learning tool, and the supervised placement of such a sensor is best discussed in an appointment.
This text serves for information and does not replace a medical examination, diagnosis or treatment. Insulin resistance and its consequences belong in medical hands, including blood sugar, fasting insulin, the HOMA index and further values. Before you begin a dietary change, intensive training or a fasting regimen, speak with your doctor, especially with existing diabetes, medications or other conditions. Weight-loss medications such as GLP-1 drugs are prescription-only and need medical supervision. This article gives no advice on sourcing or dosing.
It is not your willpower that is the problem, it is the signal
Anyone who understands insulin resistance stops seeing themselves as having a willpower problem. The body is stuck in a storage mode that can be changed. Not overnight, but step by step. When blood sugar, muscle and inflammation return to better paths, weight loss can become easier too.
Three levers you can start this week
Build in resistance training
Two short strength sessions per week, working the large muscle groups, can according to Ibáñez 2005 improve insulin sensitivity, even without the scale moving. Muscle is insulin sensitivity in action. You do not need a gym, bodyweight exercises at home count too.
Stabilise your blood sugar
Begin meals with protein and vegetables before the carbohydrates come. Favour unprocessed foods, avoid sugary drinks, and take a few minutes to walk after eating. The aim is a calmer blood sugar curve, not going without at any cost.
Protect your sleep
Sleep deprivation can worsen insulin sensitivity in the short term and drive appetite for fast carbohydrates. A regular sleep rhythm with enough hours is not a luxury, but part of the metabolic work. Start with a fixed wake-up time.
Frequently asked questions about insulin resistance and weight loss
What is insulin resistance in simple terms?
Insulin is the key that lets sugar move from the blood into your cells. With insulin resistance, the cells respond less well to that signal. The body compensates by releasing more insulin. This creates a chronically elevated insulin level, known as hyperinsulinemia. Insulin is also the body's most important storage hormone: it promotes fat storage and slows fat breakdown. Janssen described in 2021 in the International Journal of Molecular Sciences how chronically elevated insulin shifts the body's balance towards storage. That is exactly why insulin resistance can make weight loss harder, even if you do not eat more than others.
How do I recognise insulin resistance?
Insulin resistance causes no clear symptoms for a long time. Possible signs include a growing waistline, cravings especially for sweets, tiredness after carbohydrate-heavy meals, afternoon concentration dips and difficulty losing weight despite real effort. Sometimes dark, velvety skin changes appear in skin folds, on the neck or in the armpits (acanthosis nigricans). Insulin resistance can only be reliably identified through medical testing, including fasting blood sugar, fasting insulin and the HOMA index calculated from them. This text does not replace a medical examination. If you suspect it, have it checked.
What is the HOMA index?
The HOMA index (Homeostasis Model Assessment of Insulin Resistance, HOMA-IR for short) is a calculated value that estimates insulin resistance. It is derived from fasting blood sugar and fasting insulin. In simple terms: the higher both values together, the higher the HOMA index and the more likely insulin resistance. The HOMA index is used as a marker in many studies, for example in the work of Silver 2023 and Sun 2023. To be clear: the HOMA index is an approximation, not a perfect test. Interpretation belongs in medical hands, because thresholds vary by laboratory and situation.
Why am I not losing weight despite insulin resistance?
A high insulin level keeps the body in storage mode. Insulin promotes fat storage and slows fat breakdown (Janssen 2021). On top of that there is often a vicious circle: visceral belly fat sends inflammatory signals that further sustain insulin resistance (Kawai 2020 in the American Journal of Physiology). Cravings and fluctuating blood sugar make it harder to keep going. This does not mean weight loss is impossible. It means that pure calorie counting can fall short. It is often more sensible to first stabilise blood sugar, build muscle and lower silent inflammation. Then fat breakdown can become easier.
Which diet can help with insulin resistance?
The focus is on the quality of carbohydrates, not just the quantity. Sun published a multicenter RCT in 2023 in BMC Medicine with 302 participants: reducing carbohydrates lowered BMI more than pure calorie restriction. Mousavi showed in 2023 in Clinical Therapeutics, in women with metabolic syndrome, that a moderately carbohydrate-reduced diet lowered weight, waist circumference and triglycerides more strongly. In practice this means: favour unprocessed foods, get enough protein and fibre, less sugar and white flour, and build meals so that blood sugar rides as little of a rollercoaster as possible. That is a direction, not a rigid recipe.
Can exercise or resistance training help with insulin resistance?
Yes, and the effect is remarkable. Ibáñez showed in 2005 in Diabetes Care that 16 weeks of progressive resistance training in older men with type 2 diabetes could increase insulin sensitivity by 46 percent and reduce visceral belly fat by around 10 percent, and that with unchanged body weight. Muscles are the body's largest consumer of sugar. Meta-analyses by Al-Mhanna 2024 and Zhang 2023 confirm that combined aerobic and resistance training can lower long-term blood sugar (HbA1c) and inflammatory markers. So exercise here works not only through weight loss, but directly on the insulin situation.
What role do sleep and stress play?
A big one. Sleep deprivation can worsen insulin sensitivity in the short term and shift appetite, often towards more simple carbohydrates. Chronic stress raises cortisol, and cortisol can push up blood sugar and favour fat storage around the belly. From the perspective of Clinical Psychoneuroimmunology, the nervous system, hormonal system and metabolism interlock here. Anyone working on insulin resistance should not treat sleep and stress as a side issue. They are part of the picture, not cosmetics.
What is the difference from insulin resistance in women or in men?
This text looks at the weight and weight-loss topic in general. In women, insulin resistance additionally plays a special role in the interplay with the sex hormones, for example in PCOS. That is covered in depth in the article on insulin resistance and hormones in women. In men, there is a close link with testosterone, covered in the article on obesity, insulin resistance and testosterone. Both are linked. Here the focus is on the common basis: why insulin can slow weight loss and what you can change about it.
Does insulin resistance go away again if I lose weight?
Weight loss, especially around the belly, can clearly improve the insulin situation. Belalcazar showed in 2010 in the Look AHEAD study (Diabetes Care) that one year of lifestyle intervention lowered the inflammatory marker hs-CRP by around 44 percent, driven by less body fat and better glucose control. Silver 2023 found that calorie restriction reduced visceral fat by almost 10 percent. Whether insulin resistance fully reverses depends on many factors and cannot be guaranteed. But the direction is clear: less belly fat, more muscle and more stable blood sugar can favourably influence insulin sensitivity.
Are weight-loss injections like GLP-1 useful for insulin resistance?
GLP-1 medications (such as semaglutide or tirzepatide) are an effective tool that acts on a natural satiety mechanism of the body. They can favourably influence weight and metabolism. However, they are prescription-only, need medical supervision and are not a replacement for the fundamentals such as nutrition, muscle, sleep and root-cause work. Whether they fit in an individual case belongs in a medical conversation after an individual examination. This text gives no advice on sourcing or dosing.
Connections to other topics
How a glucose sensor shows your very personal blood sugar response and why supervised placement is the right first step.
Why silent inflammation makes weight loss harder and how visceral fat sustains this state. The inflammation thread of this article, in depth.
Practical directions on how to build meals so that blood sugar stays calmer and less insulin is needed.
How insulin and leptin together steer hunger, satiety and storage, and why weight is a hormonal signal.
The women's perspective with the interplay of insulin and sex hormones, for example in PCOS. Deliberately not repeated here.
The vicious circle of belly fat, insulin resistance and falling testosterone in men. The male hormone deep dive.
Sources and further reading
- Janssen JAMJL. Hyperinsulinemia and Its Pivotal Role in Aging, Obesity, Type 2 Diabetes, Cardiovascular Disease and Cancer. Int J Mol Sci. 2021;22(15):7797. doi:10.3390/ijms22157797 · PMID: 34360563 [Mechanism Review]
- Gan L, Xiang W, Xie B, Yu L. Molecular mechanisms of fatty liver in obesity. Front Med. 2015;9(3):275-287. doi:10.1007/s11684-015-0410-2 · PMID: 26290284 [Mechanism Review]
- Kawai T, Autieri MV, Scalia R. Adipose tissue inflammation and metabolic dysfunction in obesity. Am J Physiol Cell Physiol. 2020;320(3):C375-C391. doi:10.1152/ajpcell.00379.2020 · PMID: 33356944 [Mechanism Review]
- Milić S, Lulić D, Štimac D. Non-alcoholic fatty liver disease and obesity: biochemical, metabolic and clinical presentations. World J Gastroenterol. 2014;20(28):9330-9337. doi:10.3748/wjg.v20.i28.9330 · PMID: 25071327 [Review]
- Catalano PM, Shankar K. Obesity and pregnancy: mechanisms of short term and long term adverse consequences for mother and child. BMJ. 2017;356:j1. doi:10.1136/bmj.j1 · PMID: 28179267 [Review]
- Ibáñez J, Izquierdo M, Argüelles I, et al. Twice-weekly progressive resistance training decreases abdominal fat and improves insulin sensitivity in older men with type 2 diabetes. Diabetes Care. 2005;28(3):662-667. doi:10.2337/diacare.28.3.662 · PMID: 15735205 [RCT, n=9]
- Al-Mhanna SB, Batrakoulis A, Wan Ghazali WS, et al. Effects of combined aerobic and resistance training on glycemic control, blood pressure, inflammation, cardiorespiratory fitness and quality of life in patients with type 2 diabetes and overweight/obesity: a systematic review and meta-analysis. PeerJ. 2024;12:e17525. doi:10.7717/peerj.17525 · PMID: 38887616 [Meta-analysis]
- Zhang J, Tam WWS, Hounsri K, Kusuyama J, Wu VX. Effectiveness of Combined Aerobic and Resistance Exercise on Cognition, Metabolic Health, Physical Function, and Health-related Quality of Life in Middle-aged and Older Adults With Type 2 Diabetes Mellitus: A Systematic Review and Meta-analysis. Arch Phys Med Rehabil. 2023;105(8):1585-1599. doi:10.1016/j.apmr.2023.10.005 · PMID: 37875170 [Meta-analysis]
- Sun J, Ruan Y, Xu N, et al. The effect of dietary carbohydrate and calorie restriction on weight and metabolic health in overweight/obese individuals: a multi-center randomized controlled trial. BMC Med. 2023;21(1):192. doi:10.1186/s12916-023-02869-9 · PMID: 37226271 [RCT, n=302]
- Mousavi SM, Ejtahed HS, Marvasti FE, et al. The Effect of a Moderately Restricted Carbohydrate Diet on Cardiometabolic Risk Factors in Overweight and Obese Women With Metabolic Syndrome: A Randomized Controlled Trial. Clin Ther. 2023;45(3):e103-e114. doi:10.1016/j.clinthera.2023.02.002 · PMID: 36872171 [RCT, n=70]
- Silver HJ, Olson D, Mayfield D, et al. Effect of the glucagon-like peptide-1 receptor agonist liraglutide, compared to caloric restriction, on appetite, dietary intake, body fat distribution and cardiometabolic biomarkers: A randomized trial in adults with obesity and prediabetes. Diabetes Obes Metab. 2023;25(8):2340-2350. doi:10.1111/dom.15113 · PMID: 37188932 [RCT, n=88]
- Belalcazar LM, Reboussin DM, Haffner SM, et al. A 1-year lifestyle intervention for weight loss in individuals with type 2 diabetes reduces high C-reactive protein levels and identifies metabolic predictors of change: from the Look AHEAD study. Diabetes Care. 2010;33(11):2297-2303. doi:10.2337/dc10-0728 · PMID: 20682679 [RCT, n=1759]
- Dutton GR, Lewis CE. The Look AHEAD Trial: Implications for Lifestyle Intervention in Type 2 Diabetes Mellitus. Prog Cardiovasc Dis. 2015;58(1):69-75. doi:10.1016/j.pcad.2015.04.002 · PMID: 25936906 [Review]