Let’s say you want to create a fitness and nutrition plan to help a new client get the best possible results. (A typical workday, in other words.) What do you base that plan on?

A.  The best scientific evidence—randomized double-blind placebo-controlled trials are my jam!

B.  Methods I’ve used before and seen work. Real-life results trump the lab any day.

If you pick A, your plan may be too rigid for the demands and challenges of everyday life. Go with B, and your advice may be outdated.

So which option is better? Trick question. There is no better. The only good answer is both.

That’s what “evidence-based training” is all about—integrating your personal judgment based on experience with the best scientific studies. Either one alone can be limiting. But using both empowers you to seek new solutions.

My thinking is inspired by the work of David Sackett, MD, known as the father of evidence-based medicine. Based on his ideas, I’ve found four ways to make the most of this approach.

READ ALSO: Should Trainers Care About Evidence-Based Training and Therapy?

1. Keep up on the latest science

Science is always evolving. New discoveries are made; old findings are debunked. Staying on top of it gives you more options. You never know when one of them will come in handy.

Take my client John. (All names have been changed to protect privacy.) He came to me with the goal of building muscle, something he’d been trying to do on his own for many years. But because of an accident two decades earlier, lower-body training caused excruciating knee pain that lasted for days. Naturally, he’d learned to avoid it.

As it happens, I was familiar with occlusion training, a simple lifting technique that involves tying wraps around your limbs to restrict blood flow. Studies show increases in muscle growth with occlusion, even when using surprisingly light loads. Once we cleared it with his doctor, John was finally able to train his legs with little to no knee discomfort the following day.

Had I not been aware of the studies on occlusion training, I likely would’ve tried to build muscle the traditional way, using relatively heavy loads and high volume, which would’ve done nothing but cause him a lot of unnecessary pain.

It’s easy for me to tell you to spend more time reading and analyzing scientific studies. (You know, in all your free time.) You can make it easy on yourself by subscribing to a research review like MASS or Weightology. Certifications are another way to immerse yourself in exercise or nutrition science, although it can take a long time for new research to find its way into official textbooks and courses.

2. Let go of personal bias

We all process information through the filters of our personal experiences and beliefs. Taken to the extreme, these biases can narrow our focus to the point that we only pay attention to information that confirms what we already think is true, while ignoring anything that might challenge those ideas and practices.

A good trainer learns to recognize her own bias and consider other lines of thought. Instead of becoming comfortable with the status quo, she learns to challenge it. This is how trainers develop their expertise.

Rookie trainers tend to focus on a single methodology of coaching. (I know I did.) One trainer might be interested in athletic performance, so he trains all his clients like competitive athletes. Another might subscribe to the keto diet, so she coaches others to do the same.

I have one client, Sarah, who approached me with a straightforward weight-loss goal. She was young and healthy, so I put her on the same program I use for a lot of my clients: circuits and superset-style workouts to elevate her heart rate. Plenty of research backs up this type of training, and I knew from experience that it works.

But a few months later Sarah was diagnosed with a benign condition called postural orthostatic tachycardia syndrome (POTS). Symptoms include a rapid increase in heartbeat upon standing. Sarah’s heart would race when switching rapidly between moves, and it caused her a lot of anxiety.

We switched to a program emphasizing heavier lifts, with low reps and more rest between sets. The extra recovery time between movements helped her feel more in control.

I’d only used this type of training for clients with serious strength goals. I never would’ve considered it for a fat-loss client. But it was the right choice for Sarah, helping her build confidence while adjusting to the new reality of her diagnosis. It only worked because I was open to trying something new.

READ ALSO: Stop Training Your Clients Like CrossFitters, Bodybuilders, or Powerlifters

3. Get to know your client

It’s one thing to have a fully loaded toolbelt, with a mastery of both traditional and new training protocols, all backed by research and practice. But you still need to know how to pick the right tool for the job. That means always factoring in the client’s abilities and limitations, as we just showed, as well as his personal preferences and lifestyle. After all, it doesn’t matter how effective a plan can be if the client can’t or won’t follow it.

What do you know about the client’s job, family life, social activities, sources of stress and anxiety? Does she travel a lot? A workout plan requiring special equipment won’t work. Does she hate doing burpees? Don’t make them an integral part of her program.

Consider Mike, an ER doctor who routinely works 12- to 16-hour shifts. He rarely has time for a sit-down meal at work, and instead fuels himself throughout the day with pizza and vending machine snacks. You can imagine how that affects his ability to lose fat.

Interestingly, he told me that with the stress of the job, he wasn’t all that hungry at work. So I asked Mike if he’d consider modified fasting. He could consume all his calories either before or after his shift, and ignore food entirely while on the job.

There’s no magic to intermittent fasting. It can be a perfectly good way to eat less overall, but in head-to-head studies it isn’t more effective than traditional plans. But it turned out to be the best approach for Mike, allowing him to avoid hospital junk food and achieve a calorie deficit.

So how do you figure out which tool will work for your client? Try this new scientific breakthrough: Ask.

Start with questions like these at your initial consultation:

• What are your biggest priorities in life?
• Of diets you’ve tried in the past, what did you like and what didn’t you like?
• Are you satisfied with just a few bites of dessert, or do you inevitably eat more than you planned?

When you’re on the same page from the beginning, you can suggest a plan that’s realistic for the client’s lifestyle, rather than wasting everyone’s time on strategies that aren’t likely to work.

READ ALSO: Five Ways to Help Your Clients Lose Weight

4. Embrace trial and error

Whether you’re a trainer or a scientist, you won’t get far without occasional failure. You won’t learn anything if you never make a mistake or hit a dead end. Failure, on the other hand, gives you a chance to reevaluate, modify, and try something else, this time with more insight into what doesn’t work.

Think of you and your client as a scientific team: You’re monitoring performance, tracking compliance, and seeing what works best. It’s all data, and you’re gathering it together.

One client, Stephanie, is a busy mother with two young children and a demanding job at a large corporation. She regularly opted for convenience food, which was taking a toll.

Her goals were to drop some weight and boost her energy. She seemed like a good candidate for intermittent fasting, which worked so well for Mike. It would free up time early in the day so she could focus on getting the kids off to school and having a productive morning at work. By early afternoon, she could opt for something sensible for her first meal of the day. Even if it wasn’t sensible, I figured a few extra calories would be more than balanced out by eating fewer meals.

But we soon realized it wasn’t working at all. Waiting until midday was giving Stephanie license to eat whatever she wanted. Even if she wasn’t ravenous (which she sometimes was), she convinced herself she had tons of calories banked and could splurge almost daily.

We changed to a more traditional meal frequency, with an emphasis on healthy, easy-to-prepare foods that she could prep ahead of time.

That story illustrates as well as anything what we mean when we talk about evidence-based training. It isn’t about closing off options; it’s about opening them up. If a method is safe and you have good reason to believe it might work, give it a shot.

Just keep in mind that if it works for one client, that means … it works for one client. Fitness and nutrition are too individualized for anything to work for everyone.