Weight loss -- the concept of it seems so simple. You know, eat less, move more, or perhaps, eat healthy and move more. But then again, if you’re someone who’s had trouble losing weight in the past, or at least maintaining that weight loss, you may have asked yourself if genetics are to blame.
The prevalence of obesity has become a public health crisis in the United States, with more than 78 million, or one-third, of adults being obese. Obesity increases the risks of comorbidities such as diabetes, cardiovascular disease, and high blood pressure. By developing a healthy diet and increasing physical activity you can reduce body weight and improve metabolic health. Obesity treatment plans, and weight loss plans in general, focus on reducing caloric intake by at least 500 calories a day to induce weight loss of a pound per week.
When it comes to dieters, most dieters regain half to all of their original weight within three to five years. However, it’s considered a great achievement if one can even manage to maintain 5 to 10% of their weight loss. Keeping at least 3% of the original weight off is considered weight maintenance.
Your ability to lose, gain or maintain your weight is dependent on genetic, environmental, and behavioral factors. But how much of a role does genetics play in weight loss versus eating a healthy diet? Is there any truth to genetics playing a substantial role in your ability to lose weight to improve health and overall body composition? Or is diet the driving factor?
That extra pouch around your stomach had to come from somewhere, right? Your weight problems during childhood weren’t simply inherited from your parents, correct?
Well, maybe not. Maybe it’s genetics. Maybe it’s diet. Or, maybe it’s a little bit of both.
Genetics play an interesting role in body composition, especially when it comes to body fat. Your body is designed to store fat in certain places, depending on gender, age, and of course, your family genes. If you’re a woman, naturally, you’ll likely carry more fat than men since fat plays a large role in the process of reproduction. Essential fat values for men and women are 3 percent and 8 to 12 percent, respectively. Genes, however, will determine if women will carry this body fat around the hips and thighs as opposed to storing fat in the upper body. Men, on the other hand, tend to carry fat in the abdomen but can also carry fat in other places; the storage of fat, regardless of gender, can play a significant role in influencing health risks.
Could genetics cause your body to have a set body composition? Set point theory suggests that there is a specific weight range that your body may prefer. This is thought to contribute to the likelihood of weight regain following a diet. Set point theory also suggests that this ideal weight range can be genetically altered by diet or environmental factors. In light of this, one article questions if the consumption of Western diets, diets that are large in portion size and typically high-calorie, camouflages the body’s normal weight regulation.
A review published in Maturitas provides evidence that central adiposity, fatness around the abdominal area, is inherited, even after BMI has been accounted for. The researchers also stated genetics influence gender-specific body fat distribution, and DNA variants affect the maintenance and deposition of body fat, as well as body shape. So while genetics can play a role in determining your body composition, are there certain genes calling the shots? Let’s dive deeper.
One of these genes, FTO also known as the fatso gene, is a gene variant associated with the likeliness of fatness and is the common subject of research determining the role of genetics in body fat composition and obesity. FTO accounts for approximately 1 percent of BMI heritability and is heavily involved in food intake regulation. Research has also shown the FTO gene variant is linked with increased total energy intake and is also associated with childhood obesity.
According to a study published by BMJ, those who carry the FTO gene weigh, on average, 6.61 pounds (3 kg) more and are 1.7 times more likely to be obese than those who don’t carry the trait.
The BMJ research reviewed 8 studies involving 9,563 subjects to determine if FTO was a reliable predictor of obesity-related outcomes in randomized weight loss trials.
However, the study showed the FTO gene didn’t affect any changes in adiposity. In fact, those who were predisposed to obesity due to the carriage of the FTO gene responded equally well to weight loss interventions. An important note to consider is that changes in dietary and exercise habits counteract FTO’s effect on obesity.
Another study published by PLoS One investigated the effects of the fatso gene on various abdominal and peripheral fatness phenotypes and obesity-related traits in middle-aged men. The results showed a minor association between FTO and general fatness and body fat distribution.
These studies imply that genetics make a large contribution to where we store fat rather, but don’t necessarily cause us to pack on pounds.
At this point, you may be asking yourself if there’s evidence of people who are predisposed to being skinny? The answer is yes, but don’t get too excited, this hereditary trait isn’t like winning the genetic lottery. A study published in Nature identified chromosome 16 as having links to body weight. Deletion, or the removal of one of the two copies of this chromosome in each cell, is commonly linked to obesity, autism, intellectual disabilities, and an increased risk of seizure. In adults, the duplicate copies of chromosome 16 are 8.3 times more likely of being clinically underweight, which doesn’t necessarily translate to having a healthy body composition.
Researchers conducted a randomized clinical trial to determine the effects of a healthy low-fat diet compared to a healthy low-carb diet on body weight change and questioned if genetics modified those effects. The 12-month study focused on implementing reduced calorie diets that were sustainable and focused on the quality of the foods within them.
Based on our earlier discussion and what was explained about the impact genetics have on weight loss, can you guess what the major findings of the study were?
Well, both groups lost a similar amount of weight with the healthy low-fat diet group lost 11.7 pounds (5.3 kg) and the low-carb diet lost 13.2 pounds (6 kg) over 12 months. Bringing in genetics, of the 481 participants who completed the trial, 244 people had a low-fat genotype and 180 had a low-carbohydrate genotype.Though it may seem like a genetic predisposition to respond better to different foods may influence results, there was no significant diet-genotype interaction. In other words, genotype pattern wasn’t associated with the effects of weight loss, but the impact of caloric restriction likely was.
Though weight loss is simplified as calories out > calories in, remember that weight loss is more complex than that. An important aspect of diet to learn in regards to its effects on your body composition is the thermic effect of food. Also known as diet-induced thermogenesis, thermic effect describes the amount of expended energy above the resting metabolic rate it takes to digest food. For instance, protein carries a higher thermic effect compared to carbohydrates or fat. In other words, we burn more calories when we have higher protein content in our meals.
It may not only be what we eat but how we eat that contributes to the thermic effect of food. One study found that eating more quickly may reduce the thermic effects of food. This means that not only what you are eating matters, but how you eat it does, as well. When we eat too quickly, we chew less. By doing so, we may decrease the activation of important mechanisms in our nervous system that contribute to the digestion process.
Does this mean that we should just turn to eating high amounts of protein really slowly? Of course not, a well-balanced diet is important in weight loss. Organizations such as the American Heart Association and the American Diabetes Association say finding the best diet plan for you incorporates an array of fruits, vegetables, whole grains, and low-fat dairy. Yet it is controlled portion sizes that are key for not only losing weight but also preventing serious chronic illnesses such as diabetes, heart disease, and stroke.
So, we can see that in some cases, genetics can influence our weight and body composition but chances are, unless you’re a carrier for an extra or deleted chromosome 16 and your doctors say you have issues maintaining a healthy weight, genetics aren’t keeping you from losing weight.
Something else may be and that thing is, you guessed it --
A combination of a healthy diet and exercise is the most effective strategy to decreasing fat while increasing muscle. A regimen of weight training and cardiovascular (aerobic) exercise can improve muscular endurance, increase Skeletal Muscle Mass, and decrease overall Body Fat Mass by increasing fat oxidation, especially during high-intensity workouts.
However, a combination of weight training and aerobic exercise doesn’t necessarily lead to greater losses of body fat or increases in muscle mass. Researchers conducted an 8-month study on 119 sedentary, overweight, or obese adults and split them into three workout groups -- resistance training, aerobic training, and a combination of the two.
The aerobic training group and the aerobic + resistance training groups lost more total body mass and fat mass than those in the resistance-alone training group, while the resistance training group and combination group, increased their Lean Body Mass more than the aerobic-only group. But, the combination group didn’t significantly reduce fat mass or overall body mass compared to aerobic training alone.
For the record, it should be stressed again that both types of workouts have their advantages and the types of exercises you choose should be dependent on your health and body composition goals. What’s most important is that to avoid blaming genetics for your lack of progress, improving your diet and adding in a variety of exercise will help you achieve your goals much more effectively.
Based on the evidence provided in this article, though genetics play a small role in weight management and body composition, it’s clear diet has the biggest impact on weight and body composition. Understanding the roles nutrition and exercise play in your fitness goals is more important than wondering if you’re having trouble with weight loss because of hereditary factors.
If anything, the only influences your family has on your attempts to live healthier are the beliefs and attitudes towards healthy food and exercise they’ve instilled in you. In other words, you’ve inherited their behaviors towards health and wellness, which can be changed by forming new healthy habits.
So, no more blaming your weight or body composition on your mother, father, or great-aunt, who was overweight for most of her life. Sure, you may be predisposed to carrying a few extra pounds around your waist, but your body composition is up to you, your dietary habits, and your exercise habits.
Take a look at your environment, including the people you’re around all of the time. Ask yourself how changing one aspect of your surroundings can support your health and wellness goals.
If weight loss and improving your body composition is important to you, start with your diet. No diet is one-size fits all and there’s no magic bullet to developing healthier eating habits. However, as the research shows above, you’re more likely to lose those pounds by eating a healthy diet.
And if for whatever reason, you’re not convinced by now -- think of it this way, all of the credit from the results yielded from your hard work of eating a healthy, balanced diet and exercising regularly goes to you and no one else.
T'ara is a Nutrition Education graduate from American University who is passionate about mindful eating, diabetes management and living healthy through healthy cooking. She is the founder of Cooking to a T, a blog dedicated to making healthy, homemade and delicious food and blogging about living with type 2 diabetes.