How does the body turn “carbs” into “sugar”?

We hear this all the time, but what does it actually mean? I decided to look into this process and find out more …

Carbohydrates are commonly classified as being either simple or complex. The difference between a simple and complex carbohydrate is in how quickly it is digested and absorbed – as well as its chemical structure.

Simple carbohydrates

  • Often referred to as simple sugars, these carbohydrates are composed of sugars such as fructose, glucose and galactose which have simple chemical structures composed of only one sugar – monosaccharides, or double sugars – disaccharides, which include sucrose (table sugar), lactose and maltose.
  • Sugars are found in a variety of natural food sources including fruit, vegetables and milk, and give food a naturally sweet taste.
  • Simple carbohydrates are easily and quickly utilised for energy by the body because of their simple chemical structure. But they also raise blood glucose levels quickly.

Complex carbohydrates

  • These carbohydrates have more complex chemical structures, with three or more sugars linked together, known as oligosaccharides and polysaccharides.
  • Many complex carbohydrate foods contain fibre, vitamins and minerals, and they take longer to digest – which means they have less of an immediate impact on blood sugar, causing it to rise more slowly.
  • However other so called complex carbohydrate foods such as white bread and white potatoes contain mostly starch but little fibre or other beneficial nutrients.

Dividing carbohydrates into simple and complex does not account for the effect of carbohydrates on blood sugar and chronic diseases. To explain how different kinds of carbohydrate-rich foods directly affect blood sugar, the Glycaemic Index (GI) is considered a better way of categorising carbohydrates, especially starchy foods.

NOTE: the term complex carbohydrate refers to any starches, including the highly refined starches found in white bread, cakes, most pastries and many other food sources. However, when dietitians and nutritionists advise having complex carbohydrates, they are usually referring to whole grain foods and starchy vegetables which are more slowly absorbed than refined carbohydrate.

What is the Glycaemic Index?

The glycaemic index ranks carbohydrates on a scale from 0 to 100 based on how quickly and how much they raise blood sugar levels after eating. Foods with a high glycaemic index, like white bread, are rapidly digested and cause substantial fluctuations in blood sugar. Foods with a low glycemic index, like whole oats, are digested more slowly, prompting a more gradual rise in blood sugar.

  • Low-glycaemic foods have a rating of 55 or less, and foods rated 70-100 are considered high-glycaemic foods. Medium-level foods have a glycaemic index of 56-69.
  • Eating many high-glycaemic-index foods can cause powerful spikes in blood sugar. This can lead to an increased risk for type 2 diabetes and coronary heart disease.
  • Foods with a low glycaemic index have been shown to help control type 2 diabetes and improve weight loss.
Many factors can affect a food’s glycaemic index, including the following:

Processing: Grains that have been milled and refined (removing the bran and the germ) have a higher glycaemic index than minimally processed whole grains.

Physical form: Finely ground grain is more rapidly digested than coarsely ground grain. This is why eating whole grains in their whole form like brown rice or oats can be healthier than eating highly processed whole grain bread.

Fibre content: High-fibre foods don’t contain as much digestible carbohydrate, so it slows the rate of digestion and causes a more gradual and lower rise in blood sugar.

Ripeness: Ripe fruits and vegetables tend to have a higher glycaemic index than un-ripened fruit.

Fat content and acid content: Meals with fat or acid are converted more slowly into sugar.

You can find out more about the Glycaemic Index at Diabetes UK >>

These look rather tasty!

Carbohydrates and blood sugar

When we eat food containing carbohydrates, the digestive system breaks down the digestible ones into sugar, which then enters the blood.

  • As blood sugar levels rise, the pancreas secretes insulin, the hormone that enables you to digest starches and sugars. This release of insulin is sometimes called an insulin spike.
  • As cells absorb blood sugar, levels in the bloodstream begin to fall.
    When this happens, the pancreas starts making glucagon, a hormone that signals the liver to start releasing stored sugar.
  • This interplay of insulin and glucagon ensure that cells throughout the body, and especially in the brain, have a steady supply of blood sugar.
  • If you have a metabolic disorder such as diabetes that keeps you from producing enough insulin, you must be careful not to take in more carbs than you can digest.

The NHS advises that added sugars shouldn’t make up more than 5% of the energy (calorie intake) you get from food and drink each day. This is about 30g of sugar a day for those aged 11 and over.

See more about how much sugar is good for you at NHS Choices >>

Eat sensibly and enjoy good carbohydrates!

It’s important to remember that the somewhat much maligned carbohydrates are your body’s main source of energy and in fact your muscles and brain cells prefer carbs more than other sources of energy, such as triglycerides and fat, for example.  If you’re active and eating appropriately for your activity level, most of the carbs you consume are more or less burned immediately. However, if you’re eating a lot more calories per day than you are burning, then your liver will convert excess calories from carbohydrate into fats. If you consume too many calories from simple sugars like sucrose and fructose, then your body will more readily take some of those sugars and turn them into triglycerides (fat) in your liver.

  • Thanks to diabetes.co.uk
  • The Harvard School of Public Health
  • NHS Choices

Men should exercise BEFORE eating and women AFTER, to burn the most fat.

Could this really be true? Well a laboratory test carried out by Dr Adam Collins, Senior Tutor in Nutrition at the University of Surrey indicates that the amount of fat we burn changes based on whether we eat before or after exercise – and this appears to be different for men and women.

Our bodies use two main types of fuel: fat and carbohydrates – and early indications from Dr Collins’s study suggest that we could increase the amount of fat we burn just by timing when we eat with when we exercise. I was interested to discover more – like many others I had thought that exercising on an empty stomach was the way to go, but now that school of thought appears to be changing.

Michael Moseley’s team from the BBC programme “Trust Me I’m a Doctor” worked with Dr Collins on an experiment to see if it might be possible to change our eating habits around exercise to increase the amount of fat our bodies are burning throughout the day. Here are the results of that experiment:

Experiment 1: The laboratory test

Adam’s initial experiment had shown that for young men, eating carbohydrates (CHO) before exercise significantly decreased the amount of fat their bodies were burning for the 3 hours afterwards, whilst they were resting (n=10, p = 0.02, Wilcoxon matched pair tests, repeated measures 2-way ANOVA, multiple t-tests).

When he did a similar experiment with both men and women, he and his team found that whilst the men still burned less fat if they had eaten carbohydrates before exercising (n=7, p<0.05), the women burned MORE fat if they had eaten carbohydrates before exercising (n=8, p<0.05).

* Significantly different between genders: p≤0.05;
† Significantly different between treatments: p≤0.05
Total fat (g) oxidation between treatments, and genders (Exercise + Recovery).

This experiment was repeated on a single brother and sister pair, Jess and Josh, and got similar results.

Jess and Josh results:

Experiment 2: The long term effect

In order to see whether this effect measured in the laboratory could actually be significant in the real world, “Trust Me I’m a Doctor” teamed up with Adam and his research group to recruit 30 volunteers to take part in a longer term experiment.

Thirteen men and seventeen women who did not normally do a lot of exercise we chosen and for four weeks they all took part in three supervised classes a week: high intensity training, Zumba and Spin classes.

All participants had a drink both before and after each exercise class, but one of their drinks was a placebo (with no calories), whilst the other was a carefully calorie-controlled hit of carbohydrate. No one knew who was taking which drink or when.

  • Seven of the men were taking the carbohydrate drink before exercising, whilst six were taking it afterwards.
  • Seven of the women were taking the carbohydrate drink before exercising, whilst ten were taking it afterwards.

At the beginning and end of the experiment, they were tested on how much fat they were burning whilst at rest (as well as a range of other measures such as weight, waist circumference and blood sugar/fat levels).

The Results

Whilst all the women ended up burning slightly more fat at the end of the experiment, those who were taking carbohydrates before their exercise were burning more.

Difference between men and women:
Meanwhile, all the men were actually burning slightly less fat at the end of the experiment, but those who were taking carbohydrates after their exercise were better off. We saw no significant differences in their weights or waist circumference, but their blood sugar levels changed in the same way as their fat burning.
Difference between men and women:

How it works

Men and women burn fat and carbohydrate in different ways.

Men are very much ‘carbohydrate burners’ – if as a man you eat carbohydrate then your body is going to burn it rather than fat. Just giving the men carbohydrate at any time in our experiment made them burn a bit less fat! However, given that we all have to eat (and carbohydrate is an important part of our food), it is better for men to eat after exercising if they want to burn fat. This is because after exercise, men will use that carbohydrate to replace the carbohydrate in their muscles rather than burn it for fuel and will continue to burn fat instead.

For women, the results clearly show that eating before they exercise is better than eating after if they want to burn fat. Women’s bodies tend to burn fat more easily than men’s, and are not fuelled so much by carbohydrate. Moreover, women are much better at conserving carbohydrate during exercise. So when women eat carbohydrate soon after exercise, this is effectively overloading them with fuel, and interferes with the body’s ability to burn fat.

The amount of carbohydrate in our tests is probably the equivalent of a piece of toast, or a small bowl of cereal – and for men ‘not eating before exercise’ means about 90 minutes before exercise, and for women ‘not eating after exercise’ similarly means for about 90 minutes after.

Although our study was quite small, put together with the evidence from the laboratory experiments, it does seem worth us all making that simple adjustment to when we eat in order to maximise the amount of fat that our bodies burn throughout the day.

So what do you think? These studies are always interesting and I would like to see more work in this area as there does seem to be a lot of conflicting advice available on the internet today.

Super Clean Super Foods

This is my ultimate go-to nutritional guide to superfoods, telling you all you need to know to power up your plate! Keeping active and eating a super food packed balanced diet maximises your chances of achieving a healthy body. Try to build a varied diet from wholesome nutritious foods from each of these five key groups:

1. Fruit and vegetables

Try and eat at least three portions of vegetables and two portions of fruit each day. Research shows that people who eat a diet based on plenty of fresh fruit and vegetables tend to have a lower incidence of age related diseases such as heart disease, high blood pressure, cancer, dementia and cataracts. Fruit and vegetables contain a powerful arsenal of disease-fighting compounds including vitamins, minerals, fibre and phytochemicals. No single fruit or vegetable contains all the nutrients you need so it’s important to include a wide variety.

Citrus fruits are rich in immune boosting vitamin C.
  • Nitrates in beetroot improve the blood flow to your brain
  • Vitamins and phytochemicals in raspberries help protect your eyes
  • Tenderstem broccoli contains cancer-fighting phytochemicals
Vitamins and phytochemicals in raspberries help to protect your eyes.

2. Starchy carbohydrates

These come in many different guises and many of the carbohydrates we choose have been stripped of much of their fibre and nutrients. Refining wheat to produce white flour removes over half of the B vitamins, 90% of the vitamin E and almost all the fibre content. Choose unrefined carbohydrates such as wholegrains, beans and pulses, and aim to eat three portions of these every day.

Choose wholegrains instead of refined carbohydrates
  • A type of fibre found in barley called beta-glucan helps to reduce “bad”  cholesterol (LDL – low density lipoprotein).

3. Calcium-rich foods

Calcium is essential for building strong bones and teeth and is particularly important whilst bones are still growing. Aim for at least two portions of calcium each day – milk, yoghurt and dairy products are a good source of calcium as well as providing additional nutrients such as vitamins A and B2.

Dairy products are one of the best sources of calcium.

If you don’t eat dairy foods then try almonds, fortified soya or nut milk, sesame seeds, kale, broccoli and bak choy.

Broccoli contains phytochemicals and is also a good source of calcium.

4. Healthy proteins

Protein should ideally provide 15-20% of your calorie intake each day. Protein is an essential nutrient, responsible for multiple functions in your body, including building tissue, cells and muscle, as well as making hormones and anti-bodies. Choose healthier proteins such as oily fish, beans, pulses, nuts and seeds – in addition to the protein, they also contain other health promoting nutrients such as omega-3 fatty acids, vitamins and minerals.

Black beans are packed with protein and gut-healthy fibre.
  • Oily fish such as salmon, mackerel, trout and sardines are rich in omega-3 and help power your brain

5. Healthy fats

Fat is essential for your health, but most of us consume far too much of it, and the wrong sort. Eat no more than 30% of your calories each day from fat, including no more than 11% from saturated fat. Wherever possible, avoid saturated fats and trans-fats as these increase levels of LDL (bad) cholesterol in your blood. Instead opt for unsaturated fats such as olive oil and foods such as avocados, nuts, seeds and oily fish.

Avocados, oily fish, olive oil, nuts and seeds are all healthy fats.

A note about Reference Intakes (RI)

Nutritional needs vary depending on sex, size, age and activity levels so use this chart as a general guide only. The chart shows the Reference Intakes (RI) or daily amounts recommended for an average, moderately active adult to achieve a healthy, balanced diet for maintaining rather than losing or gaining weight.

The RIs for fat, saturates, sugars and salt are all maximum amounts, while those for carbs and protein are figures you should aim to meet each day. There is no RI for fibre, although health experts suggest we have 30g a day.

My thanks to Super Clean Super Foods by Fiona Hunter & Caroline Bretherton.

Come and Join the Fitness Revolution!

Metafit classes at Xercise Gym Haxby and Poppleton Road Primary School. All ages and fitness levels are welcome!

In just 30 minutes you can start to change your life. Are you ready? It’s going to be tough but I can guarantee it will be worth it. The journey starts here …

Remember: excuses don’t burn calories!
Metafit is designed to be tough and intense but the beauty of it is that it’s over and done with before you know it. Work flat out and by the end of the workout you should be exhausted. But that’s just the start of it …

Burn calories for up to 24 hours after your workout!
Workouts are usually around 22 minutes long. and if you work flat out you can expect to burn around 200+ calories. BUT, it’s the afterburn effect that is really important here. Excess Post-exercise Oxygen Consumption (EPOC) can last for up to 24 hours after exercising – during this time your metabolic rate is boosted and your body continues to burn more calories and more fat. The more intense the workout, the greater the effects will be.

Work hard – play hard!
The idea behind a good high-intensity workout is to go all out – think sprint vs. jog. To achieve true high intensity, use full-body movements that tax your cardiovascular system and build strength endurance. For example, burpees, squat jumps, sprints. Bodyweight exercises tend to be the most effective for maximum output. If you can talk while you’re doing high-intensity intervals, then you’re not working hard enough. Conversation during your workout should be impossible!

Checkout the video below to see the sort of exercises that are included in Metafit workouts … 

Work hard but don’t cheat afterwards!
It’s true that one of the benefits of HIIT is that it triggers the “afterburn effect” (Excess Post-exercise Oxygen Consumption – EPOC) which helps boost your body’s metabolism for hours after a high-intensity workout. But, afterburn is not a licence to eat everything you desire.

So remember! If you indulge in a huge cheat meal after every workout, you will never see the results you want. Don’t use HIIT to justify poor eating habits; instead, clean up your diet and not only will you have more energy for your workout, but you’ll start seeing the results – and what amazing results they will be!

You’re never too old to start Metafit!
Whether you’re 20 or 50+, a solid Metafit session is all relative to your personal level of fitness. I will adapt the exercises to suit you – the aim is to get your heart rate up to near maximal levels during the intense sets, before recovering during the short rest periods. We have all shapes and sizes in our classes and different fitness levels. And, the fitter you get, the harder you can work out!

Here we are at Xercise Gym Haxby in our Christmas T-shirts! Metafit class, Xmas 2017.

You will feel like an absolute winner afterwards. If you’ve worked yourself to your maximum during the workout, you will feel completely exhausted but elated afterwards. It’s a great feeling, particularly when you can actively see your fitness levels improving week by week.

7am metafit class at Xercise Gym, Haxby. Xmas 2017.