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Genetic Testing for Weight Loss Isn’t Worth It, Here’s What Is

Written by Dr. Ruscio on November 10, 2023

Written by Dr. Ruscio on November 10, 2023 — Reviewed by Aimee Gallo

Dr. Michael Ruscio is a DC, Naturopathic Practitioner, researcher, and clinician. He serves as an Adjunct Professor at the University of Bridgeport and has published numerous papers in scientific journals as well as the book Healthy Gut, Healthy You. He also founded the Ruscio Institute of Functional Health, where he helps patients with a wide range of GI conditions and serves as the Head of Research.

How To Lose Weight Without Expensive Tests

• Genetic Testing 101|
• Genetic Testing Limitations|
• Genetic Testing for Weight Loss|
• Natural Weight Loss Solutions|
• Gut Health and Weight|
• Healing Your Gut|
• Lose Weight Naturally|

If you’ve tried everything but haven’t seen progress on the scale, you may be tempted to try genetic testing for weight loss. I can see why this may be appealing, especially when you’ve struggled to figure out why you can’t lose weight despite trying. 

Genetic tests may seem to provide exciting, novel information that will help you finally reach your weight loss goals. But while the latest wellness-focused genetic tests make all sorts of claims about which types of diets and lifestyle changes may benefit you, unfortunately, the current research is disappointing [1, 2, 3, 4].

Direct-to-consumer genetic tests are expensive and can be difficult to interpret and challenging to translate into practical recommendations. They often lead healthcare providers (like dietitians and nutritionists) to recommend rigid rules around food, which tends to incite fear rather than empowerment. The truth is, environmental factors are far more important when it comes to body weight and weight loss (and other health outcomes) when compared to our genetic predisposition [5]. This is great news since it means we have a lot of control over what happens to us health-wise. 

Rather than spending your healthcare dollars on a weight loss DNA test that’s unnecessary and unhelpful, I would rather you use well-studied interventions that are known to be effective for weight loss like a well-balanced diet plan and exercise. These are the same interventions that will benefit you the most in the end, whether you’ve had genetic testing or not. So, rather than going the genetic testing route, you can personalize tried and true weight loss solutions like improving your gut health, practicing resistance training, spending time in nature, and creating a sleep routine, which will save you time, money, and the stress of trying to interpret genetic test results. 

In this article, I’ll discuss what genetic testing is, and why you don’t need a genetic test to help you lose weight. I’ll also share how intermittent fasting and exercise can be very helpful weight-loss tools and why poor gut health can derail your weight-loss efforts. I’ll provide a step-by-step gut-healing guide for weight loss as well. Let’s get started with some background on genetic testing.

Genetic Testing 101

It’s important to understand what genetic testing is, as well as what it can and can’t do, before we get into why I recommend against spending money on it when it comes to weight loss. 

Generally speaking, genetic testing is a DNA test that uses a sample of your blood, skin, hair, saliva, or a pregnant woman’s amniotic fluid to look for changes in genes, chromosomes, or proteins [6].

Ideally, this type of testing is conducted by a genetic counselor or qualified clinical geneticist who obtains detailed information about your medical history and symptoms in order to interpret the results accurately [7]. This type of testing can help to identify serious genetic disorders or gene-linked diseases that may impact your life or your children’s lives. Some of these include [8]:

• Breast cancer
• Colon cancer
• Cystic fibrosis
• Down syndrome
• Huntington’s disease
• Phenylketonuria
• Sickle cell disease

In addition to this type of formal genetic testing conducted by a specialist, there’s been an explosion of direct-to-consumer (DTC) wellness-focused genetic tests (like DNAfit). These tests are looking for genetic variants (permanent changes in a sequence of the DNA that makes up a gene) and single nucleotide polymorphisms (SNPs – a gene variation) [9] to make assumptions about your current or future health. 

The problem is that most gene variants don’t lead to disease [9], and most SNPs don’t have an effect on health [10], so using DNA results to draw conclusions or recommend treatment plans is quite a stretch. 

You may assume that all genetic tests are created equally, so I want to distinguish between standard and DTC DNA test kits. Here are some key differences [1, 2, 3, 4]:

• DTC tests haven’t undergone the same rigorous analytical and clinical validation that’s required for standard genetic testing.
• DTC tests typically don’t require a physician or genetic specialist to interpret the results
• DTC DNA testing companies make claims about supporting your health and wellness that aren’t supported by research.
• DTC tests often lack complete information or context [7]

I want to make it clear that genetic tests can help to identify a genetic disorder, a higher risk of developing a certain disease, or a serious gene mutation you could pass on to your children, but they can’t reasonably claim to help you optimize your general health and wellness [1, 2, 3, 4]. Let’s discuss why.

Genetic Testing: Limitations

Overall, genetic testing, whether standard or DTC, has limitations. It doesn’t provide a complete picture of health risks, and even the scientifically validated genetic tests looking at inherited conditions can’t tell you for sure that you’ll have symptoms, how severe they’ll be, or how the condition may progress over time [11]. 

In addition, DTC genetic tests make predictions based on population averages that don’t account for the variation in how each person responds to or expresses gene variants or SNPs [5]. In other words, it’s very difficult to know how you personally will be impacted by a certain gene variant or SNP because your environmental exposures and lifestyle, which impact how genes are expressed, are completely unique to you.

Complicating the issue is the fact that raw genetic information is difficult to interpret, so genetic testing companies offer third-party interpretation services to help you wade through the test results. But these services aren’t well-regulated, they have inadequate medical oversight, and they often overstate the risk of disease without any context or guidance on what to do about it [12, 13]. 

This can leave you confused and possibly fearful, which could contribute to a whole cascade of negative effects [14]. For example, if you have a SNP that’s linked to obesity, you may assume that you have no control and will automatically develop a weight problem, which may decrease your motivation with lifestyle interventions. But an analysis of genetic datasets related to obesity found the effect of SNPs on weight is likely very small, and factors in your control, like diet and exercise, are far more important [5]. 

At this point, you may be wondering if genetic testing has any benefit at all when it comes to helping you with weight loss. Research suggests no, so let’s unpack.

Genetic Testing for Weight Loss

While there are a number of genes associated with overweight and obesity, it’s important to understand that association does not mean causation. Said another way, simply having a certain genotype doesn’t mean you’re doomed to develop the disease(s) associated with it.  For example, one meta-analysis found having the FTO genotype (a polymorphism associated with obesity) had no effect on how well people responded to weight loss interventions [15].

Even when clinical trials have found evidence suggesting FTO can predict how much weight you’ll lose relative to people without the gene variant, the differences have been very small and not clinically meaningful. For example, a meta-analysis found people with a certain genotype of the FTO polymorphism lost about a half-pound to a pound compared to people with a different genotype of the FTO after 3 months to 3 years of intervention [16]. 

When looking at DTC genetic tests for weight loss specifically, a systematic review of randomized controlled trials found most people who opted for nutritionist-directed DTC genetic testing for help with dietary changes didn’t actually implement DNA diet-related changes based on the test results [3]. And even those who did, didn’t see any significant improvements in their weight or body mass index (BMI) [4]. 

The bottom line here is consumers need to understand that genetic testing for weight loss has many limitations and challenges; it’s expensive, is unlikely to provide actionable information, and may actually do more harm than good.

So, if you’ve tried diet and exercise without success and you were hoping genetic testing would give you the edge, does this mean you’re destined to just hang on to unwanted weight? Not at all. It should give you confidence that you don’t need to worry about expensive genetic testing in order to reach your weight loss goals. There are a plethora of well-validated, inexpensive strategies that can be personalized to you. Let’s take a look at how I address weight in the clinic. 

Natural Weight Loss Solutions

If you’ve gained weight or haven’t been able to lose it despite trying, it’s important to target root causes. These weight loss interventions are effective whether you have or haven’t undergone genetic testing, so you may as well go ahead and get started now.  Of course, an unhealthy diet and lack of physical activity are well-known contributing factors, so let’s start with solutions for those first [17].

Intermittent Fasting for Weight Loss

Intermittent fasting (IF) is the process of restricting food intake, which may improve your health overall by increasing autophagy, a natural detoxification process that cleans up damaged cells and encourages new cell growth [18, 19]. 

When it comes to weight loss specifically, research has found IF can lead to significant weight loss for people with excess weight [20]. In one study, obese adults lost an average of 12 pounds in eight weeks when fasting days were alternated with days of eating freely [21]. In addition, a systematic review and meta-analysis of 14 randomized controlled trials found IF to reduce body fat, waist circumference, and fat mass [22, 23, 24]

There are many ways to incorporate fasting into your lifestyle, here are some of the most common methods:

• 16:8, you fast for 16 hours per day and eat during an 8-hour window
• 14:10, you fast for 14 hours per day and eat during a 10-hour window
• 5:2, you eat normally for 5 days per week and restrict calories to less than 500 per day on 2 non-consecutive days per week
• 24-hour method, you only consume water or other non-calorie beverages for a 24-hour period one day per week.

Fasting doesn’t need to be complicated, the key here is to pick what works for your schedule and lifestyle. However, if fasting doesn’t work for you, you don’t need to force yourself to do it, there are plenty of other ways to reach your weight loss goals. Let’s talk about the importance of exercise and how you may use it to help with weight loss. 

Exercise for Weight Loss

When people think of exercise and weight loss, they often assume that they need to spend hours on the treadmill or elliptical machine at the gym. While cardiovascular exercise is very important for weight loss, resistance training may give you an important edge as it helps  increase your muscular strength and endurance by building major muscle groups [17, 25].

An overview of 12 systematic reviews and 149 other studies found people who exercise (whether using resistance training, cardiovascular training, or a combination), experienced significant weight and fat loss, but resistance training helped to reduce the loss of lean muscle mass that can often accompany weight loss [17, 26]

Resistance training incorporates exercises that use all muscle groups of the body. Common examples of resistance training include [27]:

• Body weight exercises like push-ups, squats, and lunges
• Barbell exercises like deadlifts and chest press
• Resistance bands for bicep curls and overhead presses
• Free weight exercises (dumbbells, kettlebells, and medicine balls) like bicep curls, tricep curls, and shoulder presses
• Weight machines for leg press, chest press, and back rows

I recommend both cardiovascular and resistance training as this combination approach is likely most beneficial for health overall [28, 29]. If you’re new to exercise, you may want to start with 1 day of cardiovascular exercise (brisk walking, running, cycling, elliptical) each week and 2 days of resistance training. But it’s most important to find something you can be consistent with and to avoid trying to increase your fitness level too quickly. 

Here’s a comprehensive guide to resistance training to get you started, and here’s a potential exercise schedule:

While IF and consistent exercise will likely lead to significant weight loss, another underlying issue that can make it difficult to lose weight may be poor gut health. 

Gut Health and Your Weight

Research suggests that people who carry extra weight may have leaky gut [30]. If you have a leaky gut, it will be very difficult to make headway on weight loss until it’s corrected.  

Leaky gut, also called increased intestinal permeability, is a loosening of the tight junctions between the cells that line your small intestine. When your gut is leaky, bacterial toxins, undigested food particles, and other foreign molecules can easily cross over the small intestine barrier, triggering an immune system response and inflammation [30, 31]. 

The longer the leaky gut goes on, the more likely it is to contribute to a vicious inflammatory cycle that can affect other areas of the body, giving rise to more inflammation and worsening intestinal permeability [30]. This can impair your nutrient absorption and zap your energy, which makes it more difficult to implement and stick with healthy weight loss behaviors.

Here are some contributors to leaky gut:

• Inflammatory diet
• Unmanaged stress [32, 33]
• Poor sleep [34]
• Regular alcohol use [35]
• Medications like non-steroidal anti-inflammatory drugs [36]
• Intestinal dysbiosis (imbalance of gut microbes) [37]

Fortunately, there are many inexpensive nutrition and lifestyle strategies to target leaky gut. Let’s take a look at the first two steps of my Great-in-Eight action plan for healing your gut. 

Healing Your Gut: A Step-By-Step Guide

If you’re hoping to lose weight and body fat, I recommend zeroing in on your gut health. Many of the solutions I use for healing your gut overlap with traditional (and very effective) weight loss recommendations like healthy eating and exercise. I outline the gut-healing treatment plan I use in the clinic in Healthy Gut, Healthy You but I’ll take you through the initial steps here, which can get you started on this journey. 

Step 1: Reset

In this initial step, I recommend a quick gut reset with a modified fast for 2–4 days. Using a formula like Elemental Heal, (an easy-to-digest powder mixed with water) can help to improve dysbiosis and inflammation, which may be making it difficult for you to lose weight. 

Once you get through your fasting period, you then move on to a gut-healthy, elimination diet. An elimination diet can promote great gut health by reducing your exposure to allergens and food intolerances, improving your blood sugar control, and getting you in the habit of eating more whole, unprocessed foods.

There are several dietary plans to choose from. If you’re new to making diet-related changes, the Mediterranean diet is a great place to start. If you’re eating pretty healthy already, then maybe you want to try a more restrictive option like the Paleo diet.

Follow one of these diets for a couple of weeks, and if you feel great and are noticing some weight loss and improvement in your symptoms, then continue on for a couple of months. If you feel like you need a different plan, then you may need a more restrictive option like the low FODMAP diet, which reduces the amount of certain carbohydrates that feed intestinal bacteria.

In addition to what you’re eating, it’s important to avoid grazing and instead eat every 4 hours or so, unless you feel better when you skip a meal (38) (39). And this is where you can also incorporate your IF to help with weight loss.

While you’re working on finding the right diet, there are other lifestyle factors to consider. Sleep disturbances, lack of physical activity, and excess stress can all contribute to weight gain and poor gut health (40) (39) (32). Here’s a chart with the research-backed lifestyle options and helpful tips when you’re trying to lose weight and improve your gut health:

Of course, don’t feel the need to incorporate every single one of these recommendations right from the start. Pick one or two from each category and filter them into your routine until you’re practicing them consistently. In my experience, choosing healthy lifestyle behaviors day in and day out tends to lead to dramatic improvement in gut health and body composition. The overall goal is to create an environment in the body that supports healthy gut and metabolic function and this can certainly be done without expensive genetic testing.

Once you get your diet and lifestyle squared away, you may want to consider adding probiotics.

Step 2: Probiotics

Probiotics can help support a healthy gut through a variety of mechanisms. Probiotics:

• Increase gut microbiome diversity [48, 49, 50]
• Fight harmful bugs and their toxins [48, 49, 51, 52, 53]
• Promote a more rapid recovery from dysbiosis [48, 49]
• Promote a healthy immune response in your gut [48, 49 54, 55, 56]
• Reduce gut inflammation [48, 49, 50]
• Encourage the growth of your “good” gut microbes [48, 49, 54]
• Reduce leaky gut [48, 49, 57, 58, 59]

Essentially, probiotic supplements help to improve the balance of microbes in your gut, reduce inflammation, and help to modulate your immune system, all of which can help improve your gut health and nutrient absorption. This can translate into higher energy levels, allowing you to exercise consistently and implement other healthy lifestyle changes for weight loss [60]. 

In the clinic, I recommend the triple therapy probiotic approach (using three different categories of probiotics) because most people don’t seem to achieve gut microbiome balance by just taking one strain of probiotic. 

If you want to add probiotics, here’s the process I use: 

1. Try a quality formula probiotic from category 1 (Lacto/Bifido blend), category 2 (Saccharomyces boulardii), and category 3 (soil-based) – take all three together.  
2. Monitor your symptoms for 3–4 weeks. If you’re improving, stay on this protocol until your improvements seem stable.
3. Once you’ve seen your maximum improvement, stay here for about a month to allow your system to calibrate. Then reduce your dose and find the minimal effective dose and stick with that to maintain.
   

If you’re feeling great after steps one and two, then it’s time to start reintroducing some of the foods you’ve eliminated. I recommend sticking with a maintenance meal plan of whole, unprocessed foods, but there’s no need to go to extremes when it comes to diet. The goal is to include a wide variety of foods you enjoy and a meal plan you can stick with for the long run. It’s probably a good idea to prioritize protein, which can increase your resting metabolic rate and promote muscle growth as opposed to fat storage [61, 62].

If you consistently practice IF, exercise, and complete this two-step gut-healing process but are still struggling to lose weight, you may want to move through the entire Great-in-8 step-by-step plan outlined in Healthy Gut, Healthy You. 

Lose Weight with Natural Solutions

If you feel like you’ve tried everything, but you’re still struggling to lose weight, it’s tempting to want to check out the latest fad. Direct-to-consumer genetic testing seems like an attractive option, since it promises a weight loss plan tailored to your genetic profile. But unfortunately, the research just doesn’t support this. Aside from the lack of research, these tests are expensive, they can’t provide actionable information, and they may create psychological harm.

If you want to lose weight and be successful long-term, you must address root causes like poor gut health, lack of physical activity, and poor dietary habits. Time and time again, research has found natural strategies that address diet, exercise, sleep, and stress to be very effective for weight loss. Dedicate yourself to the process outlined above, and if you’re not well on your way to reaching your weight loss goals, contact us at the Ruscio Institute for Functional Health for a more personalized solution.

The Ruscio Institute has developed a range of high-quality formulations to help our patients and audience. If you’re interested in learning more about these products, please click here. Note that there are many other options available, and we encourage you to research which products may be right for you.