It seems like the most harmless thing in the world. A client who wants to lose weight asks you, “What should I eat?”

Trainers are exposed to all sorts of nutrition and supplement information on the interwebs, in magazines and books, on social and podcasts, sometimes in actual conversations (crazy, right?). We also have years of personal and professional experience.

Put it all together, and we tend to have pretty strong opinions about what works and what doesn’t. Why wouldn’t you share some of it with a client?

I’ve been a trainer for 25 years, and yes, I sometimes talk to my clients about food. I have a diploma on my wall in sports nutrition from the International Olympic Committee, so I’m qualified to do that. But just because I’m qualified in one area doesn’t mean I should be giving nutritional advice in all areas. It might literally be illegal.

The fact is, trainers need to be careful about answering those seemingly innocuous client questions about food and supplements. You’re there to serve the client, not to make assumptions, push agendas, and give what might be recklessly misguided advice just because you have a client’s ear.

Here are some of the biggest mistakes trainers make when giving nutrition advice, along with a better strategy for each.

Mistake #1: You break the law (for real)

In California, where I live, anyone can call themselves a nutritionist and give basic advice. But it might be completely different where you live. (See below.)

What I can’t do, however, is call myself a dietitian. Registered dietitians earn that RD after their names with extensive training, and their profession is highly regulated. That’s why they’re the only ones, other than physicians, who’re legally allowed to offer medical nutrition therapy.

Put another way: If you’re not a medical doctor or an RD, you can’t say, “Eat this way to reverse your diabetes” or “stop eating this and you’re less likely to get cancer.”

You might be able to steer clients to information shown in studies or recommended by credible experts. Not sure? Find out. You need to know and understand the laws in your country, state, and or locality.

READ ALSO: Can Personal Trainers Give Diet and Nutrition Advice to Clients?

A better strategy: I never put anyone on a meal plan. I don’t tell them to eat specific foods. Instead, I tell them to (a) eat the foods they like, and (b) over time, figure out proper portions and decide if certain foods might work better based on their goals. I get great results this way.

And if a client really needs specific, reliable nutrition advice? I’ve developed good relationships with dietitians I know and trust. Referrals go both ways, since your local RDs will need good trainers to recommend to their clients. It’s a symbiotic relationship worth building.

Mistake #2: You inadvertently ridicule your client

This is big in Los Angeles, where I work: A client will come to me saying she’s doing an of-the-moment detox plan or taking some hot-right-now supplement. As tempting as it often is, you never want to respond with “damn, that’s crazy!” Or “misguided,” or “worthless,” or anything else that passes judgment on your client.

The thing she’s asking about may indeed be misguided or worthless. But if your first comment can be taken as an insult, nothing else you say matters. She’s stopped listening.

A better strategy: I tell my clients what to look out for while they try their hot new thing: “You know, there might be some concerns with that. Watch out for side effects like X, Y, or Z.”

Just mentioning the possibility of X, Y, or Z makes them more likely to experience it. (It’s called the nocebo effect, and it can be your biggest ally in the war against fad diets and crappy supplements.) You’ll develop trust with your client, and next time she'll be more likely to ask your opinion first.

I try not to hit people over the head. It’s better for both parties if they think a change is their idea and, hey, they’re lucky to have me.

READ ALSO: Five Ways to Help Your Clients Lose Weight

Mistake #3: You oversell supplements and vitamins

I don’t use many supplements. I’ve tried a lot of different things and never felt any difference. When I studied with the IOC, with the best sports nutrition teachers in the world, the only things they ever recommended were creatine, caffeine, and maybe fish oil. And the average person probably doesn’t train hard enough to see a difference with creatine. (Although creatine offers other benefits that make it worth considering.)

Meanwhile, you might be tempted to sell vitamins and supplements to give you another revenue stream. Ask yourself if it’s worth it. Research backs up only a handful of supplements, and the products aren’t regulated.

In my gym, I sell only the products and brands I use: protein powder and fish oil. I don’t do it for the income; I make less than $1,000 a year on supplement sales. I carry them as a convenience for the clients who want them.

READ ALSO: A Trainer's Guide to Protein

The better strategy: Remind your clients that supplements only help if there’s something in the diet that needs to be supplemented. Some of my female clients, for example, have a hard time eating enough protein. So for them I may suggest a protein powder or drink. It’s just food in a more convenient form.

I also warn them off some products, like pre-workout supplements with caffeine. For someone who’s already a coffee drinker, the extra boost might create a new problem.

Mistake #4: You push clients toward a diet that worked for you

Nutrition fads can become religion to some people. And once a preference for fasting or keto or paleo or vegan crosses the line into a belief system, you’ll want to proselytize to anyone who’ll listen, including your clients.

Pushing a single diet methodology on all people is a huge mistake. Your job is to help each individual get results, which means evaluating clients individually.

Intermittent fasting, for example, works really well for some of my actor clients. They might be on set at the crack of dawn or in the middle of the night, and with IF, they can go for long stretches without having to think about food. That helps them stay lean.

But if a client wants to put on muscle, I’m not going to recommend IF because it starves his body of the protein he needs throughout the day.

The better strategy: Beware of your own dogma. If you disagree with a client’s eating strategy, focus on the training program with the goal of getting long-term results. For unusual cases, refer him to an RD.

READ ALSO: How to Explain Weight Fluctuations to Your Clients

Mistake #5: You make food more complicated than it needs to be

The vast majority of our clients want to lose weight, and diet is obviously a major consideration. But a diet plan isn’t a training program. You don’t need to map out the equivalent of sets, reps, and active recovery.

In my experience, most people will eat better when they’re working out consistently simply because their mind’s in the right place. You don’t need to impose complicated rules about timing meals or weighing and measuring food unless that’s what they want, and it works for them.

The better strategy: Most clients will lose weight if they’re aware of how much they eat, and if they eat reasonable portions consistently. If you can help them in those two areas, your job becomes easy. It doesn’t matter how they get there. As long as the weekly trends are going in the right direction, I’m fine with whatever works.