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A Weighty Issue

Weight gain and eating behaviour are complex multifactorial issues and not just a simple case of eat less, move more. Some people find it easy to lose weight, while others battle to lose weight and keep it off.

We began our human journey millions of years ago and many of us have clung onto our those ancient 'thrifty genes' that mutated in order to protect the species from burning too much fuel until the next available meal was gathered. Genes also mutated so that humans could be protected and insulated from freezing temperatures. City folk certainly don't have to burn a huge number of calories pulling up to the 'drive-thru' window, nor by opening a bag of ready-prepped salad and a perfectly roasted chicken. Our food environment is constantly reminding us of how simple it is to eat.

Understanding the interaction between our genes, brain control and food environment is at the centre of this conflict, and weight gain or weight loss is not simply a matter of 'willpower'.

And yet, some people remain lean no matter what they eat and some battle the bulge constantly, even when they are not bingeing.

Our brains are wired to defend body weight. We can consciously control our choice about which diet to follow and ensure we get regular exercise, but our brains apply a subconscious strategy that is designed to defend our bodyweight as a survival and defence mechanism. The brain establishes a set point and that is what it sticks to.

Many of us have noticed that by going on a restricted diet, we lose weight, and after a nasty bout of stomach flu, the weight literally drops off. And then, little by little, over a period of 4- 24 months, that weight just creeps back up again.

This phenomenon was observed in rat studies back in the 1940's. Lab rats were left with a sufficient supply of food in their cages that kept the rats growing at a certain rate. When the rats were placed on a restricted diet, unsurprisingly, they lost weight. Once the amount of food was increased back to the pre-diet amount, the rats quickly returned to their original pre-diet weight.

The rats were then fed a diet that consisted of primarily of 'junk' food that was high in sugar and fat. The rats, got fat.

When their diet was altered back to the normal pre-binge, they lost the weight they had gained and went back to the weight they had started with before the highly palatable diet.

Humans tend to have a similar response.

Many people are emerging from the festive holiday season in January to discover that those clothes have not shrunk in the wash. Weight gain from over-eating and drinking the wrong foods produced the same results as the rat studies. Most people tend to lose that unwanted weight once their regular eating and exercise routine is back in place and just don't 'feel' that hungry.

What about those individuals who find that that 'holiday' weight does not shift so easily?

Lets get back to the brain. The brain releases hormones and other chemical messengers and we are not all the same neatly packaged clones.

Genetic differences also set us apart and 'one size' does not 'fit all'.

Some people have extremely efficient storage genes (back to the hunter-gatherer survival era) and this excess 'holiday' weight does not shrink back as expected but sticks around stubbornly gaining momentum as the years and celebrations go by.

This fat is called adipose tissue and adipose tissue is an active endocrine hormone that releases the hormone, leptin.

Leptin was discovered in 1994 (Zhang et al.) and obesity was shown to be not merely a lack of willpower. Leptin is often referred to as the hunger-hormone. Leptin, along with genes and other enzymes, is a regulator of food intake and body fat, as well as a regulator of the immune system and neuroendocrine system. Unfairly, women generally have higher levels of leptin than men.

One of leptins most important roles, is to keep the brain informed about how much fat you have stored. A bit like a fat gauge!

Fat is out long-term energy store and the brain is concerned with how long you can last once these stores start depleting.

As fat stores deplete, leptin levels in the blood go down, and the brain which has the highest energy demand in the body, sends out signals. This highly sensitive command centre, signals the rest of the organs to slow down and conserve energy. The resulting metabolic slow-down has far-reaching effects. One of them being that you will be 'encouraged' to eat more. If not, metabolism shuts down further.

Humans will all respond slightly differently and some individuals will benefit from short-term fasting, but others will be unable to follow those guidelines purely because their brains will 'make' them eat.

Remember, more than anything, the brain equates weight loss with a reduced rate of survival. That is why at a certain point during voluntary weight loss (not starvation), you simply stop losing additional weight. Your body slows down metabolically to conserve energy and your brain sends out hunger signals.

The biology-of-us and how our molecules and proteins interact within our cells comes down to our genes. Our genes are the blueprint for our biological instructions. Gene expression varies between individuals and between different population groups. Genes themselves do not write the full instruction manual. Rather, they carry the information that is transcribed and translated by the proteins in our bodies. The proteins are the actual end-product that enable our cells to function.

Twin studies have provided the most valuable genetic information and demonstrate that 70% of weight determination is hereditary.

Monozygotic (identical) twins that have been separated at birth, raised in completely different situations and then reunited as young adults, remain almost identical in weight and health patterns. However, environment plays a major role in almost everything, and if the twins are reunited much later in life, their statistics can be very different indeed.

Variations in genes such as ADIPOQ, FTO, UCP1, MC4R and PLIN (to name a few) all play a role in how individuals store and metabolise fats and carbohydrates differently. Genes also play a role in appetite well regulation, eating behaviour and even impact our food choices.

There are many occasions that we can bring into the circle of blame as well. Birthdays, anniversaries, Thanksgiving all the way to Xmas and New Year and then it starts all over again with Easter chocolates and then summer getaways.

This cycle can keep weight and hormones yo-yoing for the entire 12 months of the year.

Don't be disheartened! Have realistic expectations and goals and hopefully, there will be lots to celebrate in this new year and new decade!

By investigating and understanding your individual biochemistry and taking responsibility for your personal health, your journey to achieving a healthier balance and more responsive metabolism is within reach.


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