Removing the Fat I Couldn't Burn

I was born with MCADD: Medium-Chain Acyl-CoA Dehydrogenase Deficiency. In plain terms, my body does not handle fat metabolism in the way most bodies do. The enzyme affected in MCADD is needed to turn fat into energy, and that matters most during fasting or illness, when the body would normally lean harder on fat stores for fuel.¹

So there was a strange logic to the decision I made six years ago.

I was 6 ft 2, 220 lbs, active, and the heaviest I had ever been. My waist was 36 inches and I snored like a moose. My diet was whatever I felt like eating, and exercising did not change where I was heading. I was carrying more weight than I wanted, my blood pressure was not where I wanted it, and my glucose was less stable than I wanted it to be.

The thing I eventually chose to do was remove most of the fat from my diet.

That sounds obvious and contradictory at the same time. Obvious because I have a body that cannot use fat for energy. Contradictory because most modern diet advice points the other way: eat more fat, reduce carbohydrate, fast longer, push the body into using fat for energy. For some people that may work. For me, with MCADD, it never felt like the right bet.

This is not a protocol. It is one person’s account of what happened after I changed my diet, measured the results, and learned which parts of the change were actually doing the work.

The decision

I had about four weeks between finishing my Master’s degree and starting my PhD. I spent a lot of that time reading about diet, health and longevity. The version that kept making sense to me was a low-fat, high-starch, whole-food way of eating: potatoes, rice, oats, pasta, beans, lentils, vegetables, fruit, and as little added oil or fatty food as I could reasonably manage.

The McDougall-style framing appealed to me because it was simple. Make starch the centre of the meal. Keep fat low. Eat enough food. Do not turn every plate into a calculation.

At the time, the diet was also vegan. But that is not the most important health detail.

The lever that changed my numbers was not veganism as a label. You can eat a terrible vegan diet. You can build a vegan diet out of oil, crisps, mock meats, biscuits, and takeaway food and still be technically vegan. What I changed for health was more specific than that: I moved from fatty, energy-dense meals to low-fat, high-fibre, starch-based meals that kept me full.

The vegan part became important later, but for different reasons.

How I measured it

I did not just change my food and hope for the best. I measured everything.

I wore a Dexcom G6 continuous glucose monitor. I took my blood pressure every day. I tracked my weight and waist circumference. I watched the data closely because I wanted to know whether this was actually working or whether I was just telling myself a nice story.

I should also be honest about something here: I did this as a self-experiment, without medical supervision. That is not the route I would recommend to someone else with MCADD. MCADD management should involve people who understand your case, especially because fasting, illness, and hypoglycaemia are not minor details with this condition.²

But the data did give me something useful. It stopped the whole thing becoming vague. I was not relying on whether I felt virtuous after a salad. I could see my weight. I could see my blood pressure. I could see my glucose.

What changed

The first thing I noticed was not the weight.

Within about two weeks my digestion changed. My bowel movements were healthier, softer, and easier. That is not glamorous, but it was one of the earliest signs that my body was responding well to the food.

The second thing I noticed was satiety. I was eating big plates of food and feeling full. That mattered more than any clever theory. I knew weight loss still came down to energy balance. I was not breaking thermodynamics. Calories still count, whether you count them or not.

The interesting part was that I did not need to count them.

This way of eating let me run a calorie deficit without feeling like I was dieting. Potatoes, oats, rice, vegetables, fruit, and beans took up space. They were harder to overeat than oily, fatty, highly processed food. I was not fighting hunger all day. I was not white-knuckling my way through restriction. I was simply eating meals that made a deficit easier.

That personal experience lines up with some of the better evidence on whole-food, low-fat plant-based diets. The BROAD study, for example, used a non-energy-restricted whole-food plant-based intervention and found greater BMI reduction at six months than normal care.³ Another randomised trial of a low-fat vegan diet in overweight adults found reductions in body weight and improved insulin sensitivity, with reduced energy intake as part of the explanation.⁴

My own numbers moved quickly, then kept moving.

Over roughly six to twelve months, I went from 220 lbs to around 160 lbs. My waist went from 36 inches to about 30 inches. My blood pressure settled around 110/65. My fasting glucose, which had been about 6.5 mmol/L at the start (pre-diabetic range), became a steady 4 mmol/L (ideal for long term metabolic health).

Those numbers are not a promise. They are not what I think everyone should expect. They are just what happened to me when I changed how I ate and measured the results.

The mornings

The most clinically important part of the story was not the weight loss. It was my glucose overnight.

When I first used the CGM, I noticed I was going hypoglycaemic most mornings. Then my glucose would rise again by the time I woke up, often back toward the 6.5 mmol/L range. At the time, I did not fully understand what I was looking at. I just knew I was sleeping badly and that the trace did not look stable.

With MCADD, that is not something to shrug off. Prolonged fasting is one of the classic risk scenarios because the body cannot rely on fat metabolism in the normal way when glucose availability drops. GeneReviews describes MCADD symptoms as often appearing in response to prolonged fasting or illness, including hypoketotic hypoglycaemia.⁵

I need to be careful here, because this is exactly the kind of detail someone could over-interpret.

I do not know precisely why my morning lows were happening. I did not have a metabolic team reviewing the CGM data at the time. I suspect the combination of better food, more consistent starch intake, improved body composition, and exercise helped. But that is an observation, not a proven mechanism.

What I can say is that, over time, the overnight glucose pattern became much more stable. My sleep improved with it. That was one of the strongest signs that the diet was doing more for me than changing the number on the scale.

It is worth being clear about what “better” meant here. A glucose level that sits low but steady is not the same as one that drops into a hypo overnight and then climbs back. The first is fine. The second, with MCADD, is the part that needs watching. What changed for me was the dropping, not the average.

It is also the part I would handle differently now. If you have MCADD and you are seeing overnight lows, that is not a lifestyle curiosity. It is something to discuss with a metabolic specialist or a clinician who understands fatty-acid oxidation disorders.

Why I went vegan

The health change came first. The conviction came later.

As the diet became normal, I started reading more about the ethical and environmental arguments around animal products. That changed the way I saw the food on my plate. At first I was eating this way because it was working. Later, I stayed vegan because I no longer wanted to contribute to the industries behind animal products.

That shift mattered because it changed the diet from a temporary plan into part of my identity.

Before that, a “cheat meal” would have been easy to justify. Once the ethical part clicked, even a cheat meal had to be vegan. Not because I thought one meal would destroy my blood pressure, but because eating animal products no longer felt like something I could do and still be honest with myself.

I am not against other people eating meat or animal products. My dog is raw fed. I cook non-vegan meals for family members. My wife went vegan at the same time as me, partly out of support, and it was not a huge jump for her because she had grown up mostly vegetarian.

But no one will convince me to eat an animal product again. And I do remember how great a Sirloin steak tastes.

That is not a health change. It is an identity change.

Where it is now

It has been about six years.

I now tend to sit somewhere between 160 and 175 lbs, depending on water weight, training, muscle, and whatever else is going on. Creatine alone can push my scale weight up by about 7 lbs. But my waist has stayed roughly the same, and that has become one of the most useful measures for me.

For my own body, waist circumference and blood pressure seem closely linked. If I am around 170 lbs, give or take about 7 lbs, and my waist is below 31 inches, my blood pressure is almost always in a healthy range. If I drift outside that range, my blood pressure starts to creep up.

That is not science. It is a personal rule of thumb. It might not hold over decades as muscle, bone, age, and training change. But for now it is useful because it is simple, observable, and tied to outcomes I care about.

The diet has also changed. I am more focused on protein now because I care more about muscle than I did when I first lost the weight. That does not feel like a contradiction. It feels like the right way to treat a lifestyle: keep the principle, adjust the details. Protein quality and quantity would be a discussion in another post.

The principle is still the same. Low fat. Starch based. Mostly whole foods. Enough food to feel full. Enough flexibility to live with it.

If you have MCADD

If you have MCADD, I do not want you to read this as an argument to go vegan.

That is not the point.

The part worth taking is narrower and more practical: for me, replacing oily, fatty, energy-dense meals with lower-fat, starch-based meals was a major improvement. It helped my weight, waist, blood pressure, glucose stability, digestion, and sleep. I believe that change would have helped me even if I had never cared about animal ethics.

But MCADD is not a normal dietary context. Overnight lows, fasting, illness, exercise, and weight loss all need more care than they would for someone without a fatty-acid oxidation disorder. I did this without medical oversight, and that is not something I want to romanticise.

So if you share the condition, take the useful question rather than the whole lifestyle.

Would your body do better with fewer fat-based meals and more reliable starch-based energy?

That is a question worth taking to the people who know your case. The vegan part is mine. The duty of care is not to sell you that. It is to hand you the useful piece and leave the rest alone.

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