Genetic variations (SNPs) are one reason why we have different appetites; are satiated by different amounts of food and have different food preferences. Our genes also regulate how insulin works in our body; how many fat cells we make and how full they can get. Our genes determine how well we can break down those stored fats and use them for energy. Our individual genetic profile influences what we can and can’t digest, our tendency to gain weight, absorb important nutrients and cope with toxins.
Let’s take a deeper look into the world of nutrigenomics and weight management.
The first thing to say is that nutrigenomics is a tool in the ‘diet toolbox’ that can help you manage your weight. It’s not the whole answer, of course not, but there are some valuable insights. Let’s start with how best to balance your carbohydrates, fats and proteins.
Macronutrient Balance
You can’t have failed to hear about how different macronutrient (protein, fat and carbohydrate) proportions influence our weight. Back in the 80’s we were told to eat a “low fat” diet, more recently, “high protein” was all the rage for fat loss, then “low carb” and “ketogenic”. Why is that? Why does one weight loss study conclude that low-fat diets are the best for weight loss, while another study concludes that high-protein diets are better? One reason is our genetic differences. Our SNPs make us respond differently to different macronutrients, particularly carbohydrates and saturated fats, and your genetic report will tell you which is best for you.
Low carbohydrate diets
Some of us are genetically predisposed to release more insulin when we eat carbohydrates. The carbohydrates make us hungrier and more likely to store excess calories as body fat. So, eating a diet with about 40% of our daily calories from carbohydrates, will lower insulin and reduce fat storage and weight gain. Balanced with more protein and fat, this diet is will be naturally more satisfying, so that the overall calories consumed are naturally reduced.
Low fat diets
People who have a high sensitivity to saturated fats lose weight on a low-saturated-fat diet. Minimising animal fats such as red meat, poultry skin, full-fat dairy, eggs, cream, butter and lard will help them lose weight. Much better to eat good fats like avocados, olives, nuts, seeds, oily fish, and olive oil. It goes without saying that avoiding hydrogenated fats found in margarine, baked goods, pastries, chips, and crisps, as well as heating oils to very high temperatures are strictly off the menu for weight loss and health.
The Mediterranean diet
This diet has stood the test of time and is still one of the healthiest diets you can follow. It has been shown help people weigh less and also has lower risks for heart disease, depression, and dementia. A study was started in 1967 which recruited 120,000 nurses. The results were published in the BMJ in 2014. Those nurses who followed the traditional Mediterranean diet (lots of vegetables, fruit, nuts & seeds, pulses, fish, lean meat, olives & olive oil) most closely, had the longest telomeres. What’s a telomere, I hear you ask? A telomere is a structure that covers the end of your chromosomes and protects your DNA from wear and tear. Telomeres naturally shorten with age, by measurable amounts. So, this study (among many others) supports the benefits of the Mediterranean diet for longevity.
The Thrifty Gene
The ADRB2 gene has been called ‘the thrifty gene’. It’s one of a group of genes (PPARG TCF7L2, FABP2 and others) that conferred an advantage back in early human existence. It predisposes a reduced ability to release fat from storage, enabling the person to endure a typical feast-or-famine existence. This group of SNPs makes us sensitive to both saturated fats and carbohydrates. This means that as soon as your body senses fewer calories are being eaten (for example, on a diet) these genes then turn up your hunger sensations and turn on your cravings for higher-calorie foods. In today’s hyper-caloric society, where there is always a “feast” and no “famine”, those people with these SNPs are more likely to store body fat and become overweight. Reduction of total fat and refined carbohydrates (those that are quickly absorbed) is recommended for better weight management if you have these gene variations.
The FTO gene
One of the most studied genes is the FTO gene. It appears to regulate the amount of food we want to eat, and it impacts how well we tolerate fats, especially saturated fats. Particular SNPs on the FTO gene are also associated with obesity. But we can modify the expression of this gene. The Amish population have a high incidence of obesity-predisposing FTO gene SNPs. However, they are not an overweight population because they work manually and are very active, keeping the genes switched off. Likewise, the same was found with elite athletes, none of whom were overweight, despite some of them having the FTO SNPs. So again, it seems that high exercise levels mitigate the risk of obesity. These are nice examples of how we can influence our gene expression, using exercise, in a positive way.
If you knew you had these SNPs that predisposed to obesity, would you want to work harder to mitigate them? Would you exercise more and reduce saturated fat and refined carbohydrates in your diet? I think you would. Here’s one reason why. It has shown in studies that eating a plant-based diet (I’m not saying vegetarian), eliminating processed fats and reducing saturated fats, combined with reasonable daily exercise down-regulates the FTO gene by 30%. Research seems to show that those people who follow diets that are genetically matched to their predispositions lose more weight and keep it off.
Please note that I have singled out some individual gene variations to discuss them. But it’s really important to realise that they don’t work in isolation. Our predispositions are controlled by clusters of genes working together, not just one gene working alone. That’s why your genetic report (the results you get if you take a test) lists groups of genes, their variations, and the sum total effect of how they might all work together for you.
Fasting
Fasting is a way to modify your gene function or expression. Fasting turns on so-called ‘repair’ genes through a genetic process known as autophagy. This is a clever genetic process of ‘auto-self-destruct’ that cells go through when they have reached the end of their working life or become damaged. The cell breaks itself down and recycles the cell component parts. When you fast, the human growth hormone goes up and insulin goes down. This helps you gain muscle and burn off stored fat. Perhaps you may like to look into intermittent fasting for weight loss or weight management – there’s a wealth of positive findings supporting it.
Exercise
If I had to make one point about exercise, for weight loss, it’s this, “you can’t out-exercise a bad diet”. So, first things first: follow your genetically matched diet, then, exercise according to your power versus endurance profile (and be mindful of your injury risk and recovery needs).
Better still, take your test results to a personal trainer and let them work out the best way for you to achieve your weight-loss goals. Make your goals S.M.A.R.T (Specific. Measurable/Motivational. Actionable. Realistic. Time-based). Take small steps every day in the right direction and you will get there.
To summarise, our genes can increase or reduce our risk of developing diabetes and obesity but they don’t directly cause it. Rather, the diet we choose to eat and the activity levels we engage in each day, play the most crucial role.
In the next post, we will look at three crucial factors around genetics and ageing, DNA health, inflammation and stress.