Running to lose weight

Losing weight isn't complicated, but it isn't easy either.


I have previously written about my new-found love of running, How I accidentally became a runner. I started running in April 2022, just after I turned 46, my motivation to start was to get fit, but also to lose a bit of weight. In this blog I expand on the weight loss aspect of running. Hopefully there are some tips which might help you, but at the very least it will help me remember the journey so far and help keep me focused. I have approached weight loss the same way I have approached running or optimising a website, methodical, data driven, testing and learning.

I'm not a doctor, or a dietitian so my story is what has (and hasn't) worked for me. Buyer beware.

Warning: This blog contains some topless photographs.

Starting point, 31st March, 2022: 86.2kg

I don't actually have a proper before picture. It just didn't occur to me and perhaps I wasn't confident about my ability to actually lose weight. But here is a picture taken a couple of months before I made that decision to get fit.

Stuart McMillan, taken before weight loss started

Losing weight was the second of two key goals for when I started running, the first was getting fit. But losing weight was (and is) definitely an important objective. Or to be more exact, it isn't weight I wanted to lose, it was body fat. My waist measured 93cm, medical advice is that your waist should be less than half your height, and I am 180cm tall.

Those stats put me at a BMI of 26.6, which is classed as overweight. When I shared this with others, they said you're not overweight, you are just heavy because you have muscle, kind as those words were, it just wasn't true. Yes, I've got a bit of muscle, but I am no body builder!

I think this actually speaks to a lot of the wider problem around our overweight society, we have actually lost sight of what a healthy body shape is. I don't mean an athletic build, just the shape of the average person. It is a society-wide dysmorphia.

The Plan - Or at least it was the plan

From what I recall, back in my twenties, when I felt I was in better shape, I think I was 75kg. So, I set myself the goal in getting back there. How was I going to do it?

The healthiest way to lose weight body fat is a combination of improved diet and improved fitness.

Improved diet (without improved fitness) can create a calorie deficit and will reduce your body weight. However, with no training load, there is a good chance that you will lose muscle as well as fat.

By combining diet with fitness, you create a calorie deficit which will reduce weight (burn stored energy reserves) and maintain (or even build) lean muscle mass.

The plan was to cycle to work 3 times a week and run a couple of days a week, at the same time I was going to cut out a lot of the rubbish from my diet. For me rubbish constituted: sweet stuff (mostly chocolate) and alcohol. I was pretty sure alcohol wasn't going to be an issue, I regularly do dry months. But chocolate was going to be hard, I can eat chocolate as fast as you could hand it to me.

I knew it would not be easy or indeed quick, I expected it would take me 6 months to get down to 75kg.

Weight loss is a numbers game

The first number to know in weight loss is 7,700. That is the calorie deficit required to burn one kilogramme of body fat.

The second number is 2000. This is approximately my base metabolic rate, the amount of energy my body burns just to stay alive.

So, if I wanted to lose 11kg of body fat to take me down to 75kg, I would need a total calorie deficit of 11*7,700 = 84,700 calories. To lose it in 6 months, I would need a daily calorie deficit of 465.

That would mean that my total calorie intake per day would need to be 1500 calories, which really isn't that many. However, this is where exercise comes in. Cycling to work burns about 490 calories, that is more than my daily planned deficit! And then there is the cycle home.

This means I am burning just under 3000 calories a day (base metabolic rate + 2 cycle commutes), I can afford to eat 2500 calories and still hit my goal. 2500 calories is a quite a lot of food, it does not feel like starvation, it does not feel like punishment.

It is also worth saying, that when you are heavier, it takes more calories to move about, so you will be burning more when you exercise.

My Diet

As I've mentioned, I have been much more careful about what I eat. However, I wanted to create habits that would stick, if I was too hard on myself with my diet then I am sure there would be short term gain but in the end I would revert back to how I used to eat. I want a permanent change in my relationship with food. Previously, I would have said that the relationship I had with food was neglectful. I just didn't care enough. I'm an adult, if I wanted to eat a massive bar of chocolate then there was nothing to stop me, least of all my will power!

Firstly, I don't think of it as calorie restriction, I think of it as calorie control. Nobody watching what I eat in a day would say I was starving myself. I am just being careful to make better choices.

Intermittent Fasting

One of the big ways I have gotten in control of my calorie intake is by practicing intermittent fasting, which for me means basically not eating in the morning. If I have had a good night's sleep, then my body will have replenished my energy stores and I just don't need those calories. I was eating breakfast out of habit, not out of any energy requirements. However, I am not super strict with this. If I have exercised in the morning, then I will always have a recovery shake, containing carbs and protein. I may then have some low fat/high protein yogurt mid-morning. Recovery is more important than calorie restriction, if I am creating health and fitness habits to last years then I need to ensure that I minimise injury and maximise recovery.

Intermittent fasting was not just a way of controlling calories, I actually find it helps with mental acuity throughout the day.

Carb Reduction

I have moved aways from a lot of the carbs I used to eat, predominantly refined sugar, but also cutting back slightly on bread. Carbs are so addictive, they give you that energy boost, but then you get a crash so you want to eat more. I haven't bought a bar of milk chocolate for months, this is one waggon I do not want to fall off of. Every time I visit my folks, there are always delicious tray bakes, which I have real problems resisting, so I know that chocolate addiction is still there! At home, I just need to make sure that I don't have any in the cupboards. I have no problem resisting them in the shops, which was quite a moment for me when I realised that was the case! I do occasionally have a little bit of dark chocolate, but a little goes a long way.

Food Tracking

One of the key tools for creating a better relationship with calories has been tracking what I am eating. I use MyFitnessPal, it is excellent. It has a database of millions of foods; you can scan the barcode of just about anything and add it in to your diary. I try to be as accurate as possible when using it, I try not to lie to it. It really does help me hold myself to account.

Portion Control

Like my waistline, I am sure my portion sizes have been increasing over the years. This correlation is no coincidence. This is one area I probably could have done better, I haven't really tried to reduce my portion sizes, especially in our evening meal. However, I have tried not to let my fat-loss goals impact on family life, so we haven't really done anything different with our evening meals. I try and make sure I am well hydrated before the meal, which has been shown to reduce appetite. I have had more success at lunchtime, where I just have to get my own lunch.


Previously, most of my snacks would be carb based. I now try and make different choices, but again, none really feel like I am depriving myself. Snacks these days will more typically be fruit or veg (I love a carrot), some protein yoghurt (very filling), a protein bar (feels like a bar of chocolate, but has 20g of protein), or some oatcakes. My tactic has been snack substitution, not complete denial.


I have pretty much cut out alcohol from my life, I have had 22 units in 6 months. This feels like the least of the hardships. It's not that I don't enjoy alcohol, a nice glass of red wine in the evenings when the kids have gone to bed, or a cold cider on hot summers day when cooking pizza, or a delicious smoky single malt sat in front of the fire. But it is just not worth it. Never mind the worthless calories, I am more concerned about how it impacts my sleep and also my exercise the next day. I stopped drinking when I started tracking my sleep with my Garmin watch.


As mentioned above, after exercise I take a recovery drink, SIS Rego, which contains carbs protein and essential nutrients. But I also take a few other supplements. Firstly, a daily multi-vitamin. I also take Omega 3 & 6, as most western diets don't contain enough; I take chondroitin/glucosamine and also MSM, these are supposed to be good for joints and connective tissues, and given I have some knee issues I wanted to do all I can. The scientific evidence is out on these, but there is no harm in taking them.

I don't do caffeine. I gave it up about 4 years ago and have not been tempted back.


As a society, we have come to regard hunger as something to be avoided at all costs. We have ready access to calories whenever we want them, regardless of whether we need them. I have learned to (mostly) get over this and ignore hunger. However, I only ignore it if I am happy with my overall nutritional intake for the day so-far. That is, I listen to hunger if I need the food. After an early morning run or cycle, I know I am going to need an elevated number of calories that day and in particular, protein. I will then try and space that intake throughout the day. I am eating because I need it.

If I am hungry and I just want food (and don't necessarily need it), I will usually just ignore it, or drink a large glass of water. If it is really distracting me, I will reach for a carrot or something like that. I don't always succeed, but I am getting better. It really depends on how tired I am.

Try to be clear in your head whether your hunger is a need or just a want.


The biggest factor for me that causes fails in my diet is when I am too tired. I eat to compensate. I am tired as I write this, I let my guard down and had a bit of ice cream. Oops. Getting a good night's sleep is imperative, and I track it using my Garmin watch.

It is ok to cheat.

If you are worried about a lapse in your diet ruining your healthy eating habits, don't! You didn't make your healthy eating habit overnight and one lapse is not a trend. Put the self-recrimination behind you, it serves you no purpose; get back on that horse!

Mark Lewis, a fitness Youtuber, has a great way of putting this. He says it is fine to have that extra snack, that extra portion. Just be prepared to accept the consequences of doing so.


I am glad to say that progress has been steady. I am 6 months in and I have managed to actually beat my target of 75kg, I am now 72.2kg. My waist has gone down from 93cm to 79cm. My stomach is now fairly flat and there is the hint of a 6-pack showing through. I have mostly lost the double chins and my face isn't as round.

Stuart McMillan, 10 weeks in and 80.5kg Stuart McMillan, 18 weeks in and 76kg Stuart McMillan, 26 weeks in and 72.2kg

As well as the running and cycling, I have now taken up yoga. I have had a few issues around joints and some of the smaller supporting muscles, I need to work on balancing that out as well as increasing my flexibility and range of motion.

The New Plan

As I mentioned above, I have actually gone further than my initial plan. This wasn't an accident.

When I started, I chose 75kg as a target due to that being the weight I was when younger. But as the months went past, my thinking changed. 75kg was an arbitrary weight, it was just a number on the scales. I set out to lose body fat, so really that is the metric I should be focused on. How much body fat do I have and how much should I have?

So how much fat do I have?

I have used a couple of different methods to estimate my body fat percentage. I have some body impedance scales and I also use an online body fat calculator. Neither are perfect, but they both give similar results, my current body fat percentage is somewhere between 12% and 12.5%. This puts me the category of athlete according to the American Council on Exercise Body Fat Categorization. Men need at least 2-5% body fat, this is considered essential for health.

At 12.2% body fat, means I am carrying around 9kg of body fat. 3.5Kg of that is essential, meaning I am carrying around 5.5Kg of non-essential fat, non-essential weight.

The question I need to ask myself is how much of that non-essential weight am I happy to carry about? Being lighter will be better for my joints and will also mean I should be able to expend less energy when running (I will be moving less mass about) and therefore should be able to run longer.

I don't really need to worry about eliminating a vital energy reserve, remember each kg of fat is worth 7700 calories. That spare 5.5kg is worth a total of 42,350 calories. My longest run to-date burned 1,414 calories.

Stuart McMillan, photo taken a couple of days ago, looking thinSo basically, I could keep going and lose that further 5.5kg to take me down to 5% body fat. I would be lean, but in theory not unhealthy, and I wouldn't be doing it by tighter calorie control, I would just keep going as I have been. But I'm not gong to. Here is where dysmorphia creeps in, I look at myself in the mirror and think that I'm not that thin. My wife said I was starting to look too thin, but I thought she was exaggerating. Then I saw a picture taken a couple of days ago and I was surprised. I looked a lot thinner than I had appreciated. This was a bit of a reality check for me, a word of caution that I could go too far if I wasn't careful. It can be easy to become obsessional, to lose your balance.

This is actually where taking pictures of yourself actually comes in. It is not a vanity exercise, it is a check back on where you have come from, but is also part of the safety net that prevents you from tipping over in to harm.

The End

I am going to stop losing weight at 72kg (11% body fat), I know, another arbitrary number but it is close to where I am just now and it will just be easier to stop on a whole number of kg! I will be in the athlete category, which I am pretty pleased at given I was overweight 6 months ago.

I am hoping to maintain my body fat at 11% over the winter, the plan for this winter is to very gradually increase my running miles (not really worrying about pace) and build a solid base. When the spring comes around, I may allow my weight to drift down a little bit, just to see if being lighter helps improve my pace.

It's not easy.

It hasn't been easy to lose the weight, but it hasn't been that hard either. The exercise has been the key factor for me. My number one tip for anyone wanting to lose weight is find a form of exercise that you can do for a prolonged period. Might not be running, might be cycling (how about commuting to work by bike). Might be rowing. But find something that you can build up to doing for an hour (or more) at a moderate intensity. As soon as you start seeing some weight shifting, your motivation will skyrocket and that will help bring your diet under control.

Find what else motivates you. For me it is the numbers, I am naturally analytical, and tracking the numbers has made it into a game. But just like any game, it can get addictive, which is something to always be aware of.

I feel so much better for losing the weight. Yes, there is an element of feeling physically more well, but mostly I feel better because I feel like I own my body. I might even go so far as to say that previously I didn't feel like I owned my body so I just let anything happen to it.

Own your body, and it will be what you want it to be.

Some further reading