Unraveling the latest advice for weight management

The latest proposed approach to tackling obesity is to introduce calorie expenditure equivalents on packaging. This would mean that on a particular food item, not only would the calories be shown on the label, but how much exercise you would have to do to burn off those calories. For example, an individual packet of crisps would contain on average 131 calories, which would be the equivalent to walking for 28 minutes.

But this makes the assumption that all calories, irrespective of their origin (fat, protein, carbohydrate or alcohol) are burnt off by the body in the same way. That might be the case in a laboratory where calories are calculated by literally burning the food to see how much energy it produces, but our bodies are not comparable to a laboratory setting. For one, we host an abundance of bacteria in our digestive system and some of the food we eat feeds them, not us.

So, although this exercise-calorie equivalent may help to deter people from eating too many calories, it won’t necessarily help them to make healthy food choices.

For example, a medium avocado is approximately 232 calories and 32% fat (where almost half of which is saturated fat). If people believe that all calories are equal, then some would probably choose to eat a packet of crisps (131 cals) instead of half an avocado mashed onto a rice cake (145 cals) especially as the avocado has a lot of saturated fat. Although the calories are quite similar, they have very different nutrient content.

More importantly, certain foods are stored as fat in the body more readily than other foods. This is the case for sugars and carbohydrate foods that release their energy rapidly, including white bread, white rice and potatoes, as well as many commonly eaten breakfast cereals.

When we eat carbohydrate-based foods, depending on how quickly the carbohydrate is absorbed into our bodies, a value is given (glycaemic index, GI). High levels of sugar in the blood can be very detrimental and can lead to damage in the body (as seen in diabetics not managing their blood sugar levels). As the body is only able to store relatively small amounts of sugar (as glycogen stores), if there is an excess of sugar in the blood which triggers insulin production to protect the body from damage, the body will respond to the elevated insulin levels by storing the excess sugars in the blood as fat (in fat cells).

As long as insulin is elevated, our bodies will try and store sugars in the blood converting them to fat.

This is where it can get even more complicated as people doing intense levels of endurance sports are using up the energy quite rapidly and therefore may not have the same response to such foods. Nevertheless, there is a growing body of evidence to suggest that even endurance athletes may be wise to consider low carbohydrate fueling.

You may be thinking, "Simple, I’ll buy the product with an artificial low-calorie sweetener instead of the sugar laden food, then I won’t have the insulin issue going on". Well that’s how sweeteners have been sold to us, on the basis that we believed them to be inert substances that taste sweet and just pass though us without causing harm. That is not the case. Recent research has suggested that artificial sweeteners can disrupt our friendly bacteria (which can help to lose weight if healthy). Fortunately, there are natural sweeteners available that don’t have any where near the same impact as sugar on our insulin response.

So back to those friendly bacteria, also known as the gut microbiome. Current research is only beginning to discover the importance of our gut microbiome for our own health. Looking after our internal garden, as it has been called, may be the key to weight management and living a long and healthy life.

I am currently supporting Ben aka "365MarathonMan", who will be running 365 marathons starting with the London 2016 Marathon on 24th April and finishing with the London 2017 marathon on 23rd April 2017. One marathon a day!