How to Live to 110, a guide for all ages on how to stay healthy and live a long life.

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Next: hunger

Energy foods and calories

The foods that supply your energy

(Starch, fat, oils, sugar, protein, alcohol)

Energy foods are important. You are burning calories day and night, and these need to be replaced in your food. But if you consume too many calories, the excess is likely to be stored as body fat. And too much body fat, over time, brings a higher risk of the big killing diseases.

Unfortunately, these days vast numbers of people in the UK and across the world are putting on unhealthy amounts of body fat.

There are different ways to get your energy:

Which is best?

You may have heard that it is healthiest to get most of your calories from starchy foods such as pasta, rice, bread and potatoes. Or you may have heard that you should avoid starchy foods and that it is better to get your calories instead from protein, fats and oils. But then again you may have heard that fat, particularly ‘saturated fat’, is bad for you.

A bit confusing?

In fact, for most people it probably doesn’t matter how you get your calories, as long as you don’t overeat and put on too much body fat. That was the conclusion of a review of the evidence from lots of different studies that looked at what happened to many thousands of people.

Our book runs in detail through the different energy foods and their pros and cons. A few headline points include:

Incidentally, be cautious when you see the words ‘carbohydrate’ or ‘carb’. These are sometimes the sign of somewhat muddled or old-fashioned thinking. Your body handles sugars (other than glucose itself) quite differently from starch, so there isn’t much point in grouping them all together in a single name. Many health scientists now refer instead to ‘starch and sugars’, which is simpler and clearer.

What you can do

These different types of energy food probably make up quite a large part of your diet. It’s worth considering the points we made above – particularly if you are putting on body fat, however gradually.

What the book covers

There is a lot more to these important energy foods than we’ve covered here.

Our book has a section on each, explaining how your body reacts to them, the benefits of including them in your diet and any problems to watch out for.

Next: hunger


Glycemic index (GI)

The glycemic index is a way of describing how quickly glucose moves from food in your gut into your blood. Ideally, you want the glucose to enter your blood slowly. This keeps you feeling less hungry for longer and avoids the problems that high levels of glucose can cause in the long term.

Glycemic index is particularly useful for starchy foods. Starch is simply long chains of glucose, but some starchy foods get broken down more quickly than others.

The glycemic index of a food is measured by getting volunteers to eat a portion that contains 50 grams of carbohydrate. (Earlier, we were critical of the term ‘carbohydrate’. We’ll come back to this in a moment.) Samples of the volunteers’ blood are taken repeatedly, and the amount of glucose in the samples is measured. The changes are compared with when the same volunteers eat 50 grams of pure glucose, and a score is calculated for the food. (For mathematical readers, the score is based on the ratio of the areas under the two blood glucose graphs.)

Pure glucose is given a score of 100. If a type of food has a low glycemic index score such as 40 or 50, this means its glucose is released slowly – which is good. Beans, oats and seeds tend to have low glycemic indexes. On the other hand, potatoes and corn flakes tend to release their glucose more quickly. There is a large database XXX of GI scores for a vast range of foods.

In our opinion, though, the glycemic index has a major flaw when considering foods that contain sugar. The ordinary table sugar used in cooking and added to tea is made of half glucose and half a different type of sugar that your body treats quite differently. The glucose enters your blood very quickly, but the other type of sugar goes straight to your liver. Overall, this means table sugar has a pretty low GI score – as if its glucose was released only slowly. This is rather misleading.

This confusion is because the glycemic index is based on samples of the food that contain 50 grams of carbohydrate, rather than 50 grams of glucose (or starch). 50 grams of pure table sugar only contains 25 grams of glucose, so the GI score is around about half what it ought to be. (It’s actually a bit more than half, but the reasons for this are too detailed to explain here.)

GI is great for comparing foods that are mostly starch, but be careful if a food contains a lot of sugar. Such foods are not as good for you as their low GI score might suggest.



Selected references for the book




How to Live to 110: Longevity, living longer and the steps to take for a healthy old age