Why is it so hard to lose weight?

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Well, you may be comforted to know that it’s hard to lose weight because our bodies have evolved to cling on to stored fat, and it’s become tremendously efficient at doing it.

Its only in recent times that excess fat has become an issue. You don’t need to go back very far in our evolution to find times when storing fat was a very good thing. In the days when food was scarce and people didn’t know where the next meal was coming from, the body developed techniques to store fat and hang on to it. Fat was friend in those days. Storing energy in fat cells is also a very efficient way for the body to store it. If we had to store it in other ways, for example, through glycogen (how carbs are stored) we’d all weigh a great deal more as it doesn’t store energy as efficiently as fat cells. 

It’s only in the recent decades that our diets have changed, with higher sugar and fat content (the so called ‘western diet’), and at the same time modern life has meant that our energy use has dropped. This combination has led to excess fat and this is now a major threat to public health. In the past, it simply wasn’t a problem.   

One of the clever ways in which the body holds on to fat is by changing our behaviour when fat stores start to be depleted. The fat in our bodies secretes a protein called leptin. Leptin is secreted in proportion to the fat in our bodies so high levels of leptin are produced in the overweight and obese. When our weight starts to fall, even by a small amount, there is a disproportionately large drop in leptin.

The leptin is effectively telling that brain that more food needs to be consumed to restore fat reserves. What’s more interesting is that reduced leptin levels have an impact in our appetite and mood; we tend to feel hungry, our reward related behaviours increase and we are more inclined to feel a little down or depressed. All of this is because the body has evolved to build up fat stores and to retain them. So, when you are trying to lose weight you really are fighting your body. 

We have found other proteins that impact on appetite, such as sLR11. This protein is linked to thermogenesis, the process by which the body ‘burns’ energy to keep us warm. So, if we could trigger more sLR11 in the body, would we ‘burn’ more fat in this way? The simple answer is yes, but unfortunately it only works on special types of fat cell, brown adipocytes or brown ‘fat cells’, so even this doesn’t offer a potential solution to the obesity epidemic. Although it may be frustrating for those of us trying to lose weight, you do have to marvel at how ingenious our bodies are at managing, quite naturally, how the brain reacts to certain things. 

An enormous amount of work has been undertaken, and more is needed, to understand the systems that the body has developed to prevent us losing weight. So far, we are still to find the pill, medicine or injection that will reverse the body’s natural responses. Our bodies have evolved to be so smart that the best modern science has to offer, still can’t beat these natural reactions. 

How can you lose weight?

Weight loss surgery still remains the only proven and safe long-term weight loss solution for people with a BMI over 30 who want to achieve long term weight loss. 

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Van Patel

Van is an expert dietician and is committed to guiding bariatric surgery patients throughout their journey

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