Is it Possible to Manage Diabetes on a High Carb Diet?


It was only a couple months ago that we eagerly devoured the American Diabetes Association’s new consensus report, which gave a measured but meaningful endorsement to low- and very low-carbohydrate diets. The ADA’s panel also gave a cautious thumbs-up to vegan and very low-fat diets, listing some of the same benefits attributed to low-carb: lowered A1C, improved cholesterol, improved blood pressure, and weight loss.

I wondered to myself: is there a whole parallel world of people that successfully follow a high-carbohydrate approach to managing diabetes? Who could I find to lead me through the looking glass?

Cyrus Khambatta
Dr. Cyrus Khambatta

That’s how I got into touch with the MangoMan. Dr. Cyrus Khambatta holds a PhD in Nutritional Biochemistry and is a founder of MangoMan Nutrition and of Mastering Diabetes, a program that endorses a low-fat, plant-based, whole food diet for people with diabetes. Dr. Khambatta has Type 1 diabetes, and he eats a jaw-dropping of 500+ grams of carbs, every day.

He is also well aware of the low-carb approach. Indeed, in Mastering Diabetes lectures and podcasts, the founders frequently dismiss the low-carb diet and portray it as something of an opponent, a philosophy to be discredited and debunked. What’s he got against low-carb? I wanted to understand that, too.

We broke bread happily – metaphorically, of course, because neither of us eats much bread – and he told me that he’s actually sick of the acrimony between proponents of competing diabetes approaches: “If you’re helping people improve their health, then we’re on the same page.”


The Diet

Although Dr. Khambatta’s diet has been detailed elsewhere, I couldn’t help myself, and had to start there: just what exactly does he eat?

“My typical day of eating starts with a bowl of fruit. The bowl of fruit usually has on the order of 4 servings – so, for example, a mango, a papaya, and two bananas.

“At lunchtime I usually eat another fruit bowl, and this second fruit bowl is usually a lot larger. It’s usually double or triple the size. So that could be something like two big mangos, a papaya, four bananas.

“Dinner rolls around and I usually have something much more vegetable-centric. So I’ll eat a big salad, and when I say big, I mean I take a giant serving bowl and add everything in the fridge. Cauliflower, Brussels sprouts, broccoli, tomatoes, cucumber, chickpeas, maybe some black beans… the dressing usually has vinegar plus spices.

It’s a very low fat, low protein, very high carb diet, mostly fruits, with as much raw food as possible. My next question seemed obvious: how does he get enough protein?

“This is the number one most asked question. I’ve done a lot of research on the topic, and talked to a lot of medical professionals in the plant-based world, and it turns out that the physiological requirement for protein is much lower than most people want to believe. So I usually target about .6 g per kg body weight. If you eat the way that I describe, you’ll get close to 40g of protein in a day.”

I’m not qualified to authoritatively discuss any of Dr. Khambatta’s health claims, but I can point out that this analysis by the US Institute of Medicine shows that some studies have indeed settled on .6g per kg body weight recommendation. The panel’s final recommendation is somewhat higher (.75g per kg), and the increase seems particularly important for the young, the elderly, and women that are pregnant or breastfeeding.

What interested me most about the response is the way in which it mirrors the common myth that low-carb dieters are constantly forced to dispel: that the human body needs a certain amount of carbohydrates to function. It’s one of several parallels between the two radically different diets.


Insulin Sensitivity

Naturally, I had to ask him how he kept his blood sugar under control while eating such an outrageous number of carbohydrates. His answer, and the entire lynchpin to the Mastering Diabetes program, is his diet has hugely increased his “insulin sensitivity.” I use scare quotes around that phrase intentionally – I’m not entirely convinced that the term is appropriate in this context – but it is undeniable that the MangoMan takes an astonishingly small amount of insulin in order to process his ginormous bowls of fruit. Dr. Khambatta tends to use a mere 14 units of mealtime insulin per day, and as all low-carb advocates know, the less insulin you take, the better your control can be.

The focus on maximizing insulin sensitivity is extreme; it is emphasized in the Mastering Diabetes program even more so than is lowering A1C. Here’s how he explains it:

“Try and eat a small handful of grapes? Boom, blood glucose 280. Try and eat an apple? Boom, blood glucose through the roof. That right there is the most important test that you can take to determine your level of insulin sensitivity.”

There’s no question that many low-carb dieters complain of decreasing mealtime carb:insulin ratios. During a low-carbohydrate diet, the body often appears to lose its ability to tolerate carbohydrates. An occasional high-carb cheat meal can easily send one’s glucose soaring skyward to truly dangerous levels. But how do we know that this phenomenon is exactly the same health factor that can eventually turn into Type 2 diabetes and other related maladies?

I asked Dr. Khambatta how he measured insulin sensitivity objectively:

“If you and I were in a laboratory we’d take a euglycemic hyperinsulinemic clamp test, which is the most rugged and expensive way to measure insulin resistance at the level of the muscle and the liver. So, what I thought of, what’s a good surrogate measure that anybody could calculate at home? And it turns out, for people that inject insulin, the best measure that I’ve come up with is your 24-hour carbohydrate:insulin ratio. Take your sum total of carbohydrates and your sum total of basal and bolus insulin together, and that number is a phenomenal indicator of your baseline insulin sensitivity.”

Dr. Khambatta’s 24-hour ratio, 20:1, dwarfs my own of roughly 2:1. But it’s not clear to me that this has been validated as a true measure of insulin sensitivity. I asked him, if he was 10 times as insulin sensitive as I was, why his basal rate wasn’t significantly lower than my own. (In fact, they’re just about equal.)

“Nobody’s ever asked me that question and I’ve never even thought about it. The answer is no, there’s a floor to the amount of basal insulin that you need, and that’s independent of the diet you eat.”

I also asked him why low-carb and ketogenic diets are so often recommended for insulin sensitivity.

“If you’re coming from the Standard American Diet, which is the worst thing ever invented, chances are you’ve developed a large amount of insulin resistance. If you go from that into a low-carbohydrate diet, you’re going to improve your insulin sensitivity. The problem is that it’s very moderate. I’m talking about 30%, 40% improvement. When you adopt a low-fat plant-based whole-food diet, your insulin sensitivity is going to increase by 500%, 900%, 2,000%.”

Dr. Khambatta believes that low-carb dieters are still hugely at risk for developing Type 2 diabetes, metabolic syndrome, and associated illnesses. This seems to me another tenuous claim, one that is at odds with the conclusions of many other researchers who recommend carbohydrate restriction as the first approach to reversing insulin resistance. It is also, in my own humble and limited impression, at odds with the anecdotal experience of the low-carb community.


Blood Sugar Goals 

Despite the surprisingly small amount of insulin that he takes, Dr. Khambatta will invariably experience more blood sugar variation than will a patient on a strict low-carb diet. With a high-carb diet, no matter how finely tuned, some spikes are unavoidable. He will willingly acknowledge that a low-carb diet will result in a lower A1C and superior glucose control.

“People in the low-carb community like to flatline their blood glucose in the 80s and 90s to the best of their ability, and people that eat a low-fat plant-based diet often get criticized and told that our glycemic control is not good enough.

“The acceptable blood glucose range that we like to tell people is between 80 and 130. How did we come up with that? If you take a look at a ‘healthy’ normal nondiabetic human, their variation is somewhere between the mid-70s and as high as 140. That is considered safe and physiologically normal.

“What we like to tell people is to try and get your A1C between a 5.5% and a 6.5% with a very low frequency of hypoglycemia.

“A 4.6% A1C is not necessary. If you go and take the A1C values of 100 nondiabetic people, they’re not in the 4’s, they’re in the 5’s. If you’re going hypoglycemic more than three or four times a week, raise your A1C. I’d much prefer you have a higher A1C, even up to 6.5% or 7%, with less risk of hypoglycemia.”

From my perspective, this discussion glosses over several important factors – for example, that a low-carb diet can actually decrease the incidence of hypoglycemia, or that non-diabetics rarely linger at 140 even if they do occasionally spike that high. And while an A1C of 5.5%-6.5% would be a great improvement for a huge percentage of people with diabetes, such a modest target does tend to undercut the idea that the low-fat, plant-based, whole food diet has any special resonance for those with Type 1.

Dr. Khambatta’s regimen is intensive, and he wants his patients to weigh their portions, to exercise religiously, to constantly tweak their bolus ratios, and so on. Anyone with diabetes on any diet, even the Standard American Diet, would see improvements in A1C if they began to manage their condition with such passion. Is it the unique Mastering Diabetes diet that helps, or is it simply the detailed management? And why should a patient with Type 1 prioritize insulin resistance – the salient feature of Type diabetes – at the expense of superior glucose control?



Dr. Khambatta was aware that many ASweetLife readers are pleased with their low-carb lifestyles, and that I myself didn’t have any serious interest in going whole hog, so to speak, with the high-fruit diet. Nevertheless, I wondered if he had any other wisdom from which our community could benefit:

“Let me throw another variable into the mix that the low-carbohydrate community doesn’t concentrate on very much: nutrient density. So, in a low nutrient density environment, when the total quantity of micronutrients, like minerals, fiber, water, antioxidants, phytochemicals – when that is low, it’s necessary to have tighter blood glucose control. Is there evidence based research to back this up? No, there is not.”

That’s another claim that’s impossible to evaluate, but suffice to say that Dr. Khambatta worries that a low-nutrient diet can lead to a host of problems. When I pointed out that I myself had largely replaced flour, sugar, and other starches with larger portions of vegetables, he agreed that I had made a positive change, but still cautioned against thinking that I was as healthy as could be:

“You can still get much better metabolic health. Even though you’re feeling much better, I would argue that there’s still a long way to go.”

“People in the low-carb community say, ‘Because my A1C is so low, I am sheltered from chronic disease.’ And I’m saying no, not even close. Yes, you have a good A1C, that is good. But if you believe that your A1C is the sole indicator of your risk of chronic disease, that’s unfortunately short-sighted.”


Common Ground

I enjoyed my talk with the charming Dr. Khambatta. I didn’t accept all of his arguments – certainly not regarding the importance of insulin:carb ratio, nor his anecdotal claims that those of us successfully achieving regular normal blood sugars on low-carb diets are still at particular risk for diabetic complications – but we found much common ground. Both diets fly in the face of standard USDA recommendations, and target blood sugar control better than that advised by the ADA. We both prioritize exercise, and abstain from refined starches and processed foods.

So why then has Dr. Khambatta so routinely scapegoated the low-carb diet in his talks?

“The reason that we sort of set up the low-carbohydrate diet as the thing that you don’t wanna do is because that’s what the majority of our readers and members have been told over the course of time.”

Simply put, it’s a marketing angle. Mastering Diabetes likely does not attract many mainstream eaters. The type of person that is curious about a vegan, mostly fruit diet has probably already researched and experimented with other alternative diets, and is therefore likely to be well aware of the arguments in favor of extreme carbohydrate restriction. I take this as an affirmation of the increasing stature of the low-carb movement, which is now apparently large enough to have actually created a backlash. But when pushed, even the MangoMan will admit that the low-carb diet has improved outcomes for many.

“You’re right, the Standard American Diet is the worst.”

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3 years ago

I suspect that the the reason both approaches can work is that they manage the role of fat in metabolism. There are studies showing that fat hanging out in cells is correlated with increased insulin resistance. Simplifying here, a low-carb diet will lower the fat in the cells by burning fat for energy, while the whole-food-plant-based diet greatly reduces the fat intake limiting how much is in the system. The approaches get to the same place by different routes. Maybe. But I am not really ok with blood sugars above 100. I see the impact on my vision when it… Read more »

3 years ago

I am NOT willing to keep my kidneys on the Eve of Destruction from just a 1/2 c strawberries in my daily smoothie so even “natural sugar” is metabolized exactly the same way “added sugars” are and that is the danger of making these sound like they are two different groups in terms of the sugar content because ALL sugar behaves the same way regardless of its “natural sugar” or “added sugar” and that’s why I stopped eating the strawberries and got my A1c down to 4.7 and 4.8 for a year and a half. That’s what I call good… Read more »

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