Obesity Doesn't Cause Type 2 Diabetes, This Does
- Jun 28
- 9 min read
Dr. Michael Donaldson is a nutrition researcher and health coach specializing in type 2 diabetes reversal. As founder of End Diabetes Now and Research Director at Hallelujah Diet, he empowers people to transform their health through evidence-based, plant-centered nutrition.
Diabesity. We've been told for decades that type 2 diabetes is an obesity problem. The data says otherwise. Only one out of five obese adults has diabetes, while about one in eight “normal” weight adults do. Your BMI is merely a population-level metric and not the actual cause of the disease. The reason you have diabetes is that you've exceeded your personal fat threshold, which is a concept that reframes what reversal actually means for you as an individual.
Obesity and diabetes are not the same problem
The link between obesity and type 2 diabetes is very real. People with obesity are nearly three times as likely to develop type 2 diabetes compared to those who are of normal weight. But it's not a one-to-one correlation. If 20% of obese adults have type 2 diabetes, this means that 80% of them still don't.
Simultaneously, roughly 12% of the general U.S. population has diabetes, including millions who are of normal weight. According to CDC data, about 40 million Americans have diabetes, and a significant fraction of them would never be flagged by a standard BMI cutoff. So, type 2 diabetes is not just an obesity problem.
This is true now in 2026. It was even more true 50 years ago, when the population was generally smaller. But as the population has grown in girth, we have decided that type 2 diabetes is a weight category problem. It isn’t about BMI. It is a fat location problem, specifically excess fat within the liver and pancreas.
Roy Taylor's research changed how we understand diabetes
Professor Roy Taylor of Newcastle University has spent decades building the systematic, mechanistic case for how type 2 diabetes develops and, more importantly, how to reverse it. His twin cycle hypothesis, published in Lancet Diabetes and Endocrinology in 2019, describes the process with precision.
When a person takes in more calories than the body can safely store as subcutaneous fat, the excess begins accumulating where it doesn't belong. The liver fills up first.
Excess liver fat causes local insulin resistance, causing the liver to produce glucose even when it should not. The liver stops responding to the pancreas's signal to stop glucose production when glucose enters the body from food. So the pancreas works harder, pumping out more insulin to overcome the liver's resistance.
Eventually, fat accumulates within the pancreatic beta cells themselves, impairing their ability to secrete insulin in response to meals. This is about the time when type 2 diabetes is finally diagnosed because fasting blood sugar rises and glucose levels after meals spike tremendously high. The pancreas can no longer keep up.
In his first study, Roy Taylor and colleagues demonstrated how to reverse diabetes. In the Counterpoint study, 11 people with type 2 diabetes followed an 800-calorie diet for eight weeks. They used medical meal replacement shakes for eight weeks.
Liver fat normalized within the very first week. Pancreatic fat decreased gradually over eight weeks, and first-phase insulin secretion returned to normal. As a result, fasting blood glucose normalized quickly, even though metformin was withdrawn from subjects on day one.
The mechanism for type 2 diabetes is reversible. It's caused by excess fat accumulating in the liver and pancreas, and it goes away when that fat is removed.
What is the personal fat threshold?
In 2015, Taylor and Holman published a paper in Clinical Science introducing the personal fat threshold. Once you see it, it seems straightforward, and its simple elegance shifts the way you see diabetes.
Every person has an individual capacity to store fat safely in subcutaneous tissue. The fat sits under the skin. Some people can carry a lot. They can have a BMI of 35 or 38 without ever overloading their liver and pancreas. Others run out of safe storage space at a BMI of just 22 or 24, in the normal range.
When a person's fat storage capacity is exceeded, fat spills into the central organs, and that's where metabolic trouble begins. The personal fat threshold is not a number on a population chart. It's specific to you. It's determined by your genetics, your ethnicity, your family history of diabetes, and the lipid handling capacity of your individual cells.
You can modulate it a little bit with the food you eat. A standard physical exam doesn't reveal it, nor does your BMI. But your liver fat level does, and so does your fasting insulin concentration.
Practically, this is what it means. A person with a BMI of 38 who has never exceeded their personal fat threshold may have a healthy liver and normal insulin function. They don't have diabetes. But a person with a BMI of 24 who has exceeded their personal fat threshold may have significant liver fat, impaired beta-cell function, and type 2 diabetes.
Both of them would receive the wrong advice from a doctor who uses standard weight guidelines. Under Roy Taylor's framework, though, a person with type 2 diabetes would be told to lose weight, while a person with a lot of fat on their frame would not be given that advice because they have not crossed their personal fat threshold. There may be other benefits to losing some weight, but diabetes would not be one of them.
What does the personal fat threshold look like?
The diagram, based on Taylor and Holman's concept, illustrates three individuals. Mike has a normal BMI, Sam is obese, not just overweight, and Larry is very obese. Each of them has a different personal fat threshold marked by the dashed line.
They all used to be a bit thinner, but when they exceeded their threshold, they crossed over into diabetes, indicated by the red figure. When they lose enough weight to fall back below their threshold, they reverse their diabetes, shown by their green version.
The same mechanism is at work in all three, regardless of where they started on the BMI scale. Larry doesn't have to become as small as Mike, and Mike is in trouble with diabetes even though he's not as big as Sam. If Larry were to reverse his diabetes, he would still be larger than Sam in his red figure with diabetes. But he would be diabetes free because Larry is below his personal fat threshold, while red Sam hasn't gotten there yet.
This works even for people at a normal weight
For decades, we assumed that weight loss to reverse diabetes only worked for obese people. Normal-weight people with diabetes were thought to have a different form of diabetes that was harder to reverse.
Taylor and colleagues designed the RETUNE study specifically to test whether that assumption was correct. The trial enrolled 20 people with type 2 diabetes and a BMI below 27 kg/m2 and put them through a program of stepwise 5% weight loss cycles. They published their results in Clinical Science in 2023.
The results showed that 70% of the participants achieved remission. Average weight loss was 6.5% of their body weight. They weren't very large, so they didn't need to lose 10% of their body weight.
Measurements of liver fat and fasting insulin showed that they returned to normal. Beta cell function also improved. The same pathophysiological changes that Taylor had documented in heavier people were present and reversed in the same way.
Taylor's conclusion from the RETUNE study was very direct. The etiology of type 2 diabetes doesn't depend on BMI. The underlying mechanism is identical in people with smaller, normal, and high BMI values. The only difference between a 280-pound person with diabetes and a 160-pound person with diabetes is where their personal fat threshold sits.
You don't have to become someone you're not
Here is the really good news for you. If you have type 2 diabetes, your goal to reverse it isn't to reach some arbitrary population target. You don't have to become really skinny.
If you have a body type like Sam's or Larry's, you don't have to become as skinny as Mike to reverse your type 2 diabetes. Your goal is simply to get your liver and pancreatic fat below your personal threshold.
This may require much less weight loss than you think. In the DIRECT trial, which enrolled people with type 2 diabetes and an average BMI of about 35, 46% achieved remission at 12 months, with an average weight loss of about 10 kilograms.
In the RETUNE study, normal-weight participants achieved diabetes remission with an average loss of just 4.7 kilograms. In a study led by Brenda Davis in the Republic of the Marshall Islands, people on a plant-based diet reversed their diabetes without losing weight, simply by improving the nutritional quality of their diet, which likely reduced liver fat, though that wasn't quantified.
The empowering reframe is this. You're not trying to become a different body type. You're trying to get back below the fat level your own metabolism can handle.
For some people, that's a few pounds of visceral fat. For others, it's more substantial. But the target is personal. It's not arbitrary.
People who maintain their diabetic reversal don't regain the weight. If you regain the weight, your diabetes will return. So reversal is not a cure in the sense that diabetes can never come back. It's a reversal. You need to design a sustained lifestyle that keeps your weight below that threshold.
What if you don't have diabetes yet?
The concept of a personal fat threshold is important, even if you don't have diabetes. If your fasting insulin is elevated, your triglyceride numbers are creeping up, your fasting glucose is rising toward the prediabetic range, you have difficulty losing weight, and you're more tired than you used to be, you may be accumulating fat in places that impair your metabolism. You may be closing in on your personal fat threshold without knowing it. The difference between prediabetes and full-blown type 2 diabetes is just degrees of metabolic dysfunction. It's the same condition. If you act sooner, it's easier to reverse your condition and make yourself healthy again.
You really can't judge whether you're getting close to diabetes by whether you look overweight to other people. The question is internal.
Is your liver fat level creeping up? Is your fasting insulin level shifting into the high normal range? These can be detected with lab tests, but you have to get the right tests.
Your lab numbers tell a story your scale can't
You can't tell how your metabolism is doing just by looking at your body weight on a scale. Fasting insulin, liver enzymes like GGT and ALT, triglycerides, hsCRP, and a full thyroid panel give you a picture of where you stand relative to your personal metabolic thresholds. These aren't exotic, expensive tests. These are the tests that help measure what's happening inside your liver and pancreas years before the standard A1C triggers your doctor to tell you that you have prediabetes or type 2 diabetes.
If you want to work from your actual numbers rather than general guidelines, you can learn more about comprehensive metabolic lab testing and schedule a personal consultation here.
Final word
The personal fat threshold concept changes what reversal actually means. You don't have to match someone else's body. You don't have to become a certain body size on a BMI chart. You just need to get back down to the level of fat your own liver and pancreas can handle. For many people, that's less weight loss than they feared, and it's the right target because it's yours.
Read more from Michael Donaldson
Michael Donaldson, Nutrition Researcher & Health Coach
Dr. Michael Donaldson, Ph.D., is a leading voice in plant-based nutrition and lifestyle transformation. With a doctorate from Cornell University and more than two decades of research at Hallelujah Diet, he has helped thousands understand how food can restore health and vitality. Through his coaching platform End Diabetes Now, he guides clients in reversing type 2 diabetes naturally and sustainably. A scientist, entrepreneur, and educator, Dr. Donaldson also founded True Wealth Health Products and formulated Ora-Shield, an organic oral-care blend. His work bridges science, faith, and practical wisdom to help people achieve lasting wellness and purpose.
References:
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Taylor R, Holman RR. Normal weight individuals who develop Type 2 diabetes: the personal fat threshold. Clin Sci (Lond). 2015;128(7):405-410. doi:10.1042/CS20140553
Taylor R, Al-Mrabeh A, Sattar N. Understanding the mechanisms of reversal of type 2 diabetes. Lancet Diabetes Endocrinol. 2019;7(9):726-736. doi:10.1016/S2213-8587(19)30076-2
Taylor R, Barnes AC, Hollingsworth KG, et al. Aetiology of Type 2 diabetes in people with a ‘normal’ body mass index: testing the personal fat threshold hypothesis. Clinical Science. 2023;137(16):1333-1346. doi:10.1042/CS20230586
Lean ME, Leslie WS, Barnes AC, et al. Primary care-led weight management for remission of type 2 diabetes (DiRECT): an open-label, cluster-randomised trial. Lancet. 2018;391(10120):541-551. doi:10.1016/S0140-6736(17)33102-1
Lim EL, Hollingsworth KG, Aribisala BS, Chen MJ, Mathers JC, Taylor R. Reversal of type 2 diabetes: normalisation of beta cell function in association with decreased pancreas and liver triacylglycerol. Diabetologia. 2011;54(10):2506-2514. doi:10.1007/s00125-011-2204-7
Hanick CJ, Peterson CM, Davis BC, Sabaté J, Kelly JH. A whole-food, plant-based intensive lifestyle intervention improves glycaemic control and reduces medications in individuals with type 2 diabetes: a randomised controlled trial. Diabetologia. 2025;68(2):308-319. doi:10.1007/s00125-024-06272-8
