The BMR experiment — is it a safe and effective method to lose weight?

A few weeks ago, 10 days before my surf and yoga retreat in Portugal, I decided to follow in my friend Rahel’s footsteps, and embark on a little experiment to lose some weight before the holiday. Now, I hate to use the term ‘diet’ because I am against diet culture and everything it stands for and leads to. Also, I don’t believe this particular experiment has coined the term ‘diet’, so for the purpose of this blog post we will stick to the term “the BMR experiment’.

In a similar way to Rahel, I had been enjoying the start of Summer by indulging in a few ice creams and BBQs over the weekends. Even though I rarely drink alcohol apart from on special occasions, I had the odd G&T and glass of Prosecco (well, if you do drink, you may as well go posh, right?) here and there. But as we all know, these types of foods are inflammatory and what they lead to are the familiar feelings of waking up a little hungover, bloating, fatigue, bad skin, etc. etc. “But hey, isn’t it about everything in moderation?”, I hear you cry! Of course that’s true, and also it is what I preach to my clients. But it’s also about changing behaviours for the long-term and it’s amazing how quickly bad habits can stick around for a little too long. So whilst this experiment was definitely for a short-term gain only (and there’s a reason for that as you’ll find later on), it did make me think that putting a few principles together from the BMR experiment would yield incredible results in the long-term, just without the ‘restriction’ part. Besides, everyone wants to feel a little more confident wearing his or her swimwear on the beach on holiday, right?

So what exactly is your BMR? BMR stands for Basal Metabolic Rate and is the amount of energy expended while at rest. So for example, if you were sedentary for an entire day (e.g. you were ill, bed bound from an injury, or just desk-bound at work for most of the day) your body requires a certain amount of calories to keep your vital organs functioning. Everyone’s BMR total calorie figure will be different, just as much as our physiologies are different. But Rahel and I had spoken about how this experiment theoretically would be manageable, successful and healthy in terms of rapid weight loss, and would call BS on all the calorie-restriction diets. Both of us have never come across anyone with a BMR below 1200 calories.

I have to say I was a little apprehensive before starting this experiment, especially after watching Rahel go through it first. We are both Personal Trainers and both lead very active lifestyles. Rahel didn’t train very much over her 10-day period, though I pretty much continued my regular routine of training and working. I currently train 3–4 times a week on top of teaching classes (relatively low-impact), training my clients and doing Yoga and Pilates 4–5 times a week. So you can already tell I am not your ‘average 9–5 office job worker’, and how possibly this experiment would affect me more than someone less active. As a consequence I was more concerned about how to sustain a reasonably high level of energy and not crash too often. This was mainly due to the fact we were entering the start of the high-temperature days of the heat wave we’ve had this Summer in London. I also had started to suffer badly from hayfever, which had developed into a cold by the start of the experiment. Not the best starting point…

My BMR is 1331 calories, with my maintenace calories being 1863. I tracked all my calories through MyFitnessPal and worked out my macros so that I didn’t go over around 30–35% of my total cals in fat, approx 35% protein and 40% carbohydrates. I cut out alcohol and a lot of sugar from my diet (apart from natural-occurring sugars). I didn’t eat out in the evenings, but if I did grab lunch from somewhere I made sure it was still easy to track my macros. Meals were balanced and as a result of my total daily calories, I had three meals per day with very limited snacking.

Instead of breaking down the experiment on a day-by-day basis, I have instead written below my learnings and outcomes across the 10 days.

1. Be prepared.

I mean this in terms of your meals, but being ‘mentally prepared’ helps, too! A lot of the time I went high protein due to the high-calorie foods, such as refined carbohydrates and fat. I have done high-protein diets before and there’s a reason these are so successful when it comes to weight-loss. You feel satiated from protein-rich meals and don’t get that surge in blood-sugar levels leading to the inevitable ‘crash and burn’ feeling in the afternoon. I am lucky enough to have most of my meals at home and rarely need to eat out on-the-go. So I made sure in my weekly food shop that I chose fresh veg (organic where possible), low-fat protein options (lean meats, eggs, yoghurts, etc.) as I didn’t have room in my daily caloric allowance for highly palatable foods for they give you a lot of calories and very little gross volume to actually fill you up.

I would often batch cook omelettes with lots of vegetables, so I would be able to eat as soon as I got home for lunch. Alternatively I would keep it simple with a salad and have all the ingredients ready to throw together. With salads, however, you just have to be careful with the dressing (whether home-made or shop-bought), as these usually contain more calories than the salad itself!

I would also have to think wisely about dinner as I cook for my husband as well. This usually meant that my serving size was much smaller than that of my husband’s. Another key point to weight-loss is serving size, particularly if you do cook for your family. The tendency is to either pile the food on to fill your entire plate, or to give yourself the same serving size as your partner. Unknowingly you could be adding 250–350 extra calories to your total daily intake.

2. Don’t track/record your exercise/energy expenditure.

As a nation we overestimate our energy expenditure on a daily basis. We are less active than we think so we should always set our low activity maintenance calories as the base. This is one of the most important reasons why I tell my clients to listen to their bodies. You can always eat more if you’ve physically had a very strenuous day or exercised a lot, and feel the need to top up energy levels with more food. But we can also fall victim to using food as a ‘reward’ because we went to the gym that day, or we did a spin class, or we walked 20, 000 steps. Physical exercise is a stressor on the body, just as much as having a mentally exhausting day at work is also stress on the body. Stress in whatever form it comes in elevates our cortisol levels. And what happens when our cortisol levels are high? We eat more and our sleep is affected and this turns into a vicious cycle. By keeping my energy expenditure out of the equation, I was able to focus on just my calorie intake from food.

However, as I mentioned earlier, I still remained physically active throughout the experiment through my training and job, and it was only a few days in where I started experiencing fatigue due to the heat, but also the sensations of ‘hangry’. Which leads me nicely on to point 3…

3. Caffeine helped me A LOT.

Most of you know that I love my coffee, but I rarely ever have more than two cups a day and never past 2/3pm. THAT ALL CHANGED with this experiment!

The power of a coffee, particularly a cold brew mid-afternoon on a hot day, is just magical, and it was everything I needed to fuel my afternoon/evening, resist the cravings and continue with my day. I would nearly always get my cravings in the afternoon and so a coffee with milk (I never have sugar in my tea or coffee) would keep me satiated and help me stay focused.

Luckily it didn’t affect my sleep, even though my last coffee of the day would be at around 4/5pm in the afternoon. If you don’t already know, caffeine remains in your system for up to 7 hours so for some people who are heavily reliant on caffeine and drink upwards of 3–4 cups a day, this can have a detrimental effect on their sleeping patterns.

So all in all, during the experiment I still rarely had more than 3 cups of tea or coffee per day. This includes green tea, which also has a high caffeine content.

4. When your emotions get the better of you, don’t panic! Keep focused.

The average caloric deficit for weight loss is -500kcal a day. My BMR calories are nearly 600kcal lower from my maintenance, which meant I knew I would lose weight faster than normal, especially with the exercise I was still doing. As a result, over the 10 days the most I went over my BMR calories was 140 calories. If you know me I don’t do anything by halves — it’s all or nothing! So I was determined to get the most out of this experiment by staying as close to my BMR cals as possible! I had also kept myself accountable by documenting my progress (the good, the bad and the ugly!) on Instagram, so that kept me focussed throughout the 10 days.

This didn’t stop me getting the dreaded CRAVINGS. Oh my dear Lord. By the 5thday, I had ridiculous cravings for pizza! So much so that wherever I went all I could think of, dream of and see was pizza. It was only made worse when all you have for dinner at home waiting for you is chicken and veg and a salad. Tough times.

I would usually get these cravings after doing my training, which makes perfect sense as after exercise you have depleted your glycogen stores, so your body is craving some carbohydrates to refuel your muscles and to give you some energy!

So after having had enough of experiencing the cravings, I didn’t give myself a hard time for going over my BMR cals slightly because I needed something substantial to eat after my workout. Remember, how closely you follow the BMR experiment is up to you; you just may not reach your end goal as efficiently as you’d like.

Even though I didn’t eat out and socialise during the experiment, I know too well from my clients that this is where old habits start crawling back into motion and where they find it almost impossible not to cave in to social pressure and lose will power.

When you dine out and socialise, you can still stay under your maintenance calories and continue weight loss as planned, even if it’s slightly slower some days. So many restaurants note nutritional information on their menus now, so it’s still possible to stay on track. If the menus lack the nutritional information, then how about prepping yourself in advance and checking the menu options online. If you have had experience in tracking your macros before, you can make sensible decisions based on the calorie content of meals you have regularly. And when it comes to alcohol, who says you have to drink? You are in control, remember. Are a couple of social occasions where you’re not drinking really going to be the end of the world for you and your friends? In fact, who cares what they think? Don’t let your emotions get the better of you, don’t make excuses and keep yourself accountable.

Results and Conclusion

In 10 days I went from 58.4 kg to 55.5 kg. Interestingly enough I hadn’t lost body fat, although I only used my body composition monitor and not measurements, so it’s hard to say how accurate my scales are. I think most of the weight was water retention, but you can clearly see more muscle definition in my abdominals from the above photos, and a slimmer frame overall.

What is even more interesting is that when I returned from my holiday in Portugal (predominantly vegan/vegetarian diet and I only had one alcoholic drink all week), the scales showed 56.9kg and more than 2% loss in body fat! Go figure! It may have taken a week of going back to more maintenance calories and a lot of physical exercise (surfing) to kick-start my metabolism again and burn some fat!

If you read Rahel’s account of her BMR experiment, the whole point of this process was not primarily to lose weight, as we all know that is a given! If your energy expenditure is higher than your energy intake, you will lose weight. Remember, your BMR calories are the baseline calories your body NEEDS to keep functioning, and should be sufficient to keep an individual running from day to day, allowing them to lose weight fast but in a safe manner. I trained throughout the experiment, and as a result suffered a lot more from depleted energy levels. In hindsight I should have been sensible and reduced my training considerably. I was increasing my energy expenditure by up to 400–600 calories on some days, and this fact alone has largely dictated my overall conclusion below. For active individuals, a standard weight loss diet with at least an extra 200–300kcal on top of BMR calories would be necessary.

Conclusion

If you’re trying to lose weight only, but have no time for the gym and are leading rather a sedentary lifestyle due to work, the BMR diet may be for you. But even then, I would suggest this for the short-term and certainly over ANY ‘crash diet’ or ‘restriction diet’. By following the advice above, it is a sensible and sustainable way to lose weight over a short period of time, particularly if you have an important event coming up like a holiday, Birthday, a wedding to attend (note that I didn’t say your wedding as no bride needs that extra thing to worry about!).

However, this experiment was NOT for someone as physically active as myself, and I think I have proved that. The extra calorie burn every day literally “ate into” my caloric allowance leaving me feeling low in energy, ‘hangry’ and really stressed and moody.

What it certainly helped me with is made me more mindful about food and what I was eating. I wasn’t mindlessly snacking throughout the day, just because I could or because I’m a physically active PT. My meals were more balanced and I knew that if I did this experiment for a few weeks that I would have integrated a few more days where I would have allowed myself to go to my maintenance calories.

Whatever ‘diet’, exercise regime or biohacking experiment you decide to follow, my advice always is to listen to your body. What works brilliantly for someone else might not work for you, but hopefully it will help instil some new positive behaviours and banish bad habits.