A Weighty Issue #3 - Why go low carb?

When I began this weight loss journey I thought that I was fairly informed. However, the one question I kept coming back to was 'Why do certain diet plans work?' And, secondly, what was I doing wrong when I wasn't following some sort of plan?

The answer wasn't hard to find. And it's not rocket science. 

Whether it's Atkins, Lighter life, SlimFast, Weightwatchers or any other diet plan, success is achieved by putting fewer calories into your body every day than your body needs. Therefore, once all of these new calories are used up, the body has no choice but to start using the reserve tank, which is your body fat.

Image: Shutterbug on Pixabay

In basic terms, a kilocalorie (kcal) – commonly referred to as simply a ‘calorie’ - is a unit of measurement for the amount of energy contained in food or drink. About 20% of the calories we take in are used by the brain, 18-26% is converted into mechanical energy that’s used by our muscles, and the rest is used by other organs and internal processes like digestion, blood production etc. In order to run efficiently our bodies need, on average, around 2500 kcals per day for men and 2000 for women. So, if you put in less than that, you'll lose weight. Simple.

Another way to lose weight is to burn calories by increasing  activity. However, exercise is a pretty inefficient way to do it. You’d need to do an hour of vigorous cycling or swimming to burn off the 250kcals contained in one jam doughnut and, incredibly, a whole 15 minutes of weightlifting just to compensate for the calories in a Granny Smith apple (62kcals). Exercise has plenty of other benefits besides weight loss, of course, and should be encouraged. It helps us to retain muscle mass and tone – something that gets harder to do as we get older - and improves heart and lung function. And it’s no great secret that walks in the countryside or at locations that we find beautiful or awe-inspiring are very good for our mental health (more on that in a later post). But, when it comes to losing weight, the simplest and best solution is to say no to the doughnut and cut the calories going down your throat. 

So, where were all the calories coming from in my diet? Was it fat? Was it sugar?

Image: S Hermann & F Richter from Pixabay

What cruel whim of evolution made chocolate so addictive and rice cakes taste like polystyrene packaging? 

Actually, evolution had nothing to do with it. This is a problem of our own making. 

Carbohydrates are the sugars, starches and fibres found in fruits, wholegrains, vegetables and dairy products. They are essential to our wellbeing as they provide roughage, which is good for our digestive system, plus a wide range of nutrients such as vitamins and minerals. The fibre in carbs also ‘bulks out’ a meal so that you feel fuller for longer. Natural ‘good’ carbs metabolise slowly into blood sugars (glucose) that supply us with a continuous source of energy throughout the day. 

However, not all carbs are good carbs.

So-called 'bad carbs' are only bad because we’ve made them that way. They are the original Frankenstein Food. They are mostly found in products that don’t occur in nature like refined sugar, bread, pasta, pastry, beer etc. They may have started life as good carbs - like those found in wheat, corn and sugar cane - but we then process, refine and alter them. Most of the fibre and nutrients are stripped away with the result that they are metabolised super quickly into glucose. This results in a ‘sugar rush’ (glycaemic high) which provides a pleasurable and instant burst of energy. 

However, the downside of this is that the body now finds itself in possession of far more glucose than it needs and the sudden spike sets off alarms in the pancreas. This leads to the production of extra amounts of the hormone insulin, which turns the excess sugars into fat for storage. It’s a handy survival mechanism that evolution gave us so that, whenever there was a sudden glut of energy-rich carbs, our ancestors could store the excess like a squirrel stocking up on nuts for the winter. It improved their odds of living through times of famine. 

Image: pasja1000 from Pixabay

But we now live in an age of 24 hour drive-through burger restaurants and triple choc brownies. Carb gluts are all too easy to find. And the ‘sugar rush’ we experience triggers our brains’ reward system. A neurotransmitter called dopamine is released, which makes us feel good (drugs like cocaine and nicotine do the same). This, naturally, makes us want to eat more bad carbs. Also, any high is usually followed by a crash as blood sugar levels return just as quickly to normal. That also makes us crave more. 

I’m sure you’ve all experienced the phenomenon of eating a substantial meal full of bad carbs and then, an hour later, you're hungry again. That’s the brain screaming ‘More!’ 

To make the situation even worse, the more bad carbs we eat, the more dopamine is released by our reward systems. As the result, the brain starts to adapt to the frequency of stimulation and our dopamine receptors start to dull. All of which means that we need more and more bad carbs to get the same ‘fix’. It’s not quite an addiction but it’s pretty damned close. 

So what’s the answer? 

To reduce our bad carb intake. This allows the receptors to sharpen up again so it takes less glucose to make us happy. Which is why many diet plans seem to work but fail once we come off them. Having been denied many of the foods we love, we instantly go back to our old ways of eating and the dopamine receptors get reset to 'More please!'

The good news, however, is that the body responds pretty quickly to reductions in blood glucose (certainly much more quickly than it does to reductions in other addictive substances). If you decide to go ‘cold turkey’ you’ll get through the worst of it in a matter of days rather than weeks. It's true. I love bread. I love making bread. I love cakes and buns and biscuits. The smell of a bakery is Nirvana to me. But, after just a week of cutting my intake substantially my cravings completely disappeared. It's extraordinary.

But surely fat is the problem isn't it? That's why there are all those fat free or low fat products on the market.

Image: Free_Photos on Pixabay

To be sure, too much fat (like too much of anything) is bad for you, especially when they are saturated or trans fats. But, when it comes to weight loss, fat isn't the villain. It's the henchman.

We’ve known that refined sugar is bad for us for decades but the sugar industry is very rich and very powerful and also has the advantage of good PR. We associate sugar with words like sweet, treacly, syrupy, candied. Fat, on the other hand, has almost no positive associations because it’s both a foodstuff and an outcome. Everyone wants to be sweet, but no one wants to be fat. Plus, there is no international fat lobby to exert pressure on governments in the way that the multi-billion pound sugar industries used to. So fat has become the scapegoat for our muffin tops, jelly bellies and thunder thighs and we've all bought into the lie by eating low fat or fat-free products. 

However, because they don’t taste as nice without the tasty mouth-coating fat, cheaper foods often get loaded up with bad carbs - usually refined sugars - as a substitute. Consequently, the number of calories in low fat foods is often not much different from full fat foods. 

As an example, I went to buy myself some black cherry flavoured yoghurts and discovered that a 125g full fat black cherry yoghurt contains 99 kcal while the low fat alternative has ... 98 kcals.  

A tub of Wall's Soft Scoop Vanilla Light Ice Cream (30% less fat) = 163 kcal per 100g (73 kcals per 100ml scoop). Compare that with Wall's full fat Soft Scoop Vanilla Ice Cream = 186 kcal per 100g (82 kcal per 100ml scoop). Yes, there's 30% fat. But there isn't 30% fewer calories. 

M&S Reduced Fat Traditional Coleslaw 300g = 164kcals per 100g, while M&S Deli Coleslaw 300g = 206kcal per 100g. That seems to be a bit of a difference doesn't it? But I can promise you that 'deli' means extra ingredients (e.g. Single cream, sugar, potato starch, salt etc.) over and above fresh healthy shredded veg and a bit of mayo. Compare the calorie count with a Morrison's budget 'Savers' Coleslaw. No additions, no bells or whistles and just just 81kcals per 100g.

Even better - make your own!

So, to sum up ... 

The advice on any decent website about weight loss - including the NHS - can be distilled down into three basic rules:

1. For weight loss, focus on TOTAL calories. Don't be deceived by low fat and 0% fat products. Check the labels for total calorie count.

2. To lower blood sugar, count the carbs. Your daily carb count should amount to around 45% of your daily calorie intake BUT eating bad carbs will leaving feeling hungry and wanting more, while the good carbs won't. As a sample calculation - a woman aiming for a daily limit of 2000kcals can have up to 900kcals from carbs. To work out how many grams of carbohydrate there ae in 900kcals, just divide by four. So 2,000 calories x 0.45 = 900kcals. 900kcals ÷ 4 = 225 grams of carbohydrates per day. 

3. For heart health, reduce fat. A single gram of fat provides nine calories, so lowering fat intake is an efficient way to cut down on total calories AS LONG AS it's not been replaced by carbs like sugars. And the fat you do eat should be unsaturated - such as we get from plants, oils, seeds, nuts and oily fish. Saturated fats (from animals and dairy mostly) and artificial  trans fats (found in fried foods like doughnuts, baked goods and some margarines) can raise your bad (LDL) cholesterol and lower your good (HDL) cholesterol, which results in an increased risk of cardiovascular disease. 

I've focussed on reducing my consumption of calories overall. I cut back heavily on my consumption of bad carbs and I've avoided as much saturated fat as possible (see my previous post on meat eating). And the weight has fallen off at a rate of 2-3lbs per week. But I've been eating lots of amazing, satisfying, tasty food and I almost never feel hungry. On top of which, I've not banned any particular foods or drinks. 

As I've written previously, I've re-educated myself to treat things like beer, chocolate and cake as treats rather than staples. As the result, I'm slimmer, my diabetes is in remission, and I enjoy them more because they are treats. Like the guy who works in a chocolate factory, if you can have something every day, it soon stops being special.

So there you have it. The old adage of 'moderation in all things' proves true once again.

Of course, the next question I faced when starting out was, 'How do I keep track of what I'm eating?'

More on that in my next blogpost.


  1. Here's an interesting comment to this blog by Bill Pope over on Facebook: 'My work got a dietitian in recently to talk to us about looking after our mental health. It turns out a lot of us have been cutting out fat because we’ve been more sedentary in lockdown. Disaster. Brains are made of fat, protein and water. We’ve been practically inviting in burnout, fatigue, anxiety and depression.
    Pass me that wholemeal bacon butty …' Interesting, eh?


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