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A dietitian’s advice on how to lose weight in a healthy and positive way

February 1, 2024
6 min
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Marily Oppezzo is a learning and behavioral scientist, registered dietitian and nutritionist, exercise scientist, and lifestyle medicine practitioner. She studies the ways in which movement can be used to enhance physical, cognitive, and psychological health. Dr. Oppezzo is the head of the nutrition pillar at the Stanford Lifestyle Medicine Program, and has been providing diet advice to athletes, active adults, patients with cardiac disease for 20 years.

Marily Oppezzo, PhD, MS, RD, DipACLM

Instructor of Medicine

Stanford Prevention Research Center

Stanford School of Medicine 

Are there any new findings or a new approach to weight loss in 2023?

Yes! For one the wild open west of the microbiome. Nobody has dialed in the what or the exact why yet, but we do have enough interesting studies to be excited by this. 

For example, mice are bred to be what’s called “obesigenic”, meaning they are bred to eat more. When you give them a fecal transplant with the microbiome of lean mice, they lose weight. It’s too early to know how to act on that knowledge specifically, but we know that following a whole-food, plant-based, diverse diet – like trying new things and not always having the same foods – is the best way to promote a healthy gut!

Another new approach is time restricted eating. It encourages you to eat on a predictable schedule, which is lovely for your body. There’s some evidence your body and organs work on circadian rhythms too, so giving it a heads up for “it’s time to eat” helps it consistently carve out space to do important things that can’t be done while eating or digesting. It also provides clear cut rules which are easier for people to follow rather than making many micro decisions every day.

Another one is trying to make lots of lifestyle changes early on before actively focusing on losing weight. There’s amazing work by Michaela Kiernan where people try to make changes to their life without trying to lose weight and instead trying to maintain their weight. They explore different healthy foods, loving desserts without the guilt, adapting with fewer calories the day after an over indulgence, and self-compassion BEFORE they try to lose weight. By developing these skills without the pressure of weight loss, this group was shown to lose weight AND keep it off more than the group who tried to lose weight first.

Finally, I don’t like to talk about weight loss too much because that’s an outcome-focused goal. Yes, it’s measurable and can help you track progress, which is great for any goal pursuit, but it focuses too much on the outcome and not the process. If you don’t love the process, it’s going to be really hard and ultimately unsatisfying to achieve the outcome. I think shifting people’s focus to the idea that there are a lot of approaches to a lot of different healthy behaviors that can help people lose weight will be more beneficial. For example, what if one month you make an effort to try 3 brand new vegetables and ways of eating them, and you end up with 5 that you like? Maybe you don’t lose a ton of weight for that small move, but you’ve discovered new healthy food options you can replace high calorie junk food with. This will help with weight loss in the long run.

Not every single one of these ideas will be perfect for everyone at every moment – but we have to sample the menu of options in creative ways to see what sticks and works for us.  

Let’s assume someone has tried lots of weight loss methods before that didn’t work. What are 3 things you’d recommend them to do?

- Sleep is so important. Every one of us knows how many priorities melt away and our ability to handle even mild stressors gets detonated after a spate of bad sleep. Even if you think you’re fine on little or bad sleep, your body doesn’t. Sleep deprivation puts your body in a physiological state of stress. Lack of sleep increases ghrelin (your hunger “I want to eat” hormone) and decreases response to the leptin messages (your “hey, I’ve had enough” hormone). Plus, you crave quicker energy to handle the stress (like unhealthy snack options vs. healthier ones). So, physiologically your body is set up to thwart your weight loss attempts, so sleep hygiene and getting a good night sleep is an important approach. I personally have suffered from decades of debilitating insomnia. But because I know the importance of sleep (even beyond weight loss), I’ve learned to practice self-hypnosis (like with Oneleaf) to better manage my stress and improve my sleep.

- Redirect your efforts for a month. Take a break from the scale as the determinant of how you are going to feel that day, and focus completely on starting a different healthy habit. Maybe it’s learning pickleball. Maybe it’s starting a meditation practice. Maybe it’s finding quicker and easier ways to eat something healthy that isn’t processed. Maybe it’s doing small bouts of exercises throughout your day to break up long hours at the desk required for your job. Pick something that could aid in weight loss but that isn’t weight loss and redirect your focus and goals there for a month.

- Start a strength training practice. While it’s not going to burn a huge amount of calories, maintaining your muscle tissue is one of the most important things you can do for your body as you age, but also as you lose weight. If you aren’t eating enough protein, especially when you eat less calories, your body might chomp down on our thigh muscles to compensate. Strength training can help minimize that loss, and have your body go for the fat more than the muscle.

- Self-monitoring. It’s a pain to watch and record your food. But even if categorizing your food high-level in terms of “points” or “stoplight” (red, yellow, green foods), the evidence shows that you will modify your behavior over time.

What are common weight loss and nutrition myths? Can you help us debunk some?

- All carbs are bad. People have swung so far away from what we see in science by believing that all carbohydrates are going to be “indulgent” or “weight gainers”. Christopher Gardner did a study that showed that on average, people lost the same amount of weight on the healthiest versions of low fat and low carb - within both diets, you can see people who do well and who have less success. I think we need to give carbs a makeover or a reputation manager. Healthy, intact carbs are healthful plant-based foods that can offer a number of phytonutrients, fiber, and micronutrients. But some camps would say it’s better to have hamburger meat than wheat berries. That’s just flat out not supported in the research.

- People are worried about eating fruit, and that’s an unhealthy myth. Fruit is wonderful for you. It contains so many phytochemicals, fiber, micronutrients that are super healthy. Just eat them in fruit and not juice form. It takes a long time to eat an orange, but 3 seconds to drink 14 of them.

- We can use the glycemic index to help control our sugars and personalize our diets. A lot of people are stoked about the glycemic index, or the index that measures average responses to 100 grams of different foods on blood sugar responses. I just don’t find it that useful. No one eats 100 grams of a single food with nothing else. Also, within a person our responses to the same foods can be widely variable. I eat the same breakfast every day, and depending on my sleep the night before and my state of stress, my blood sugar response is totally different. 

- Weight loss is a matter of willpower. This is a detrimental myth, and a lot of weight loss ads and marketing perpetuates this myth. There are a number of factors that we can’t measure or identify that help contribute to our body weight and how easy it is to lose and maintain the loss of it. Calories in, calories out is a consistent win, but it’s not that cut and dry for everyone. The work I talked about with the obesogenic mice shows the possibility that it’s not always about what you eat and controlling it. Other factors impacting weight loss are sleep, psychological stress, psychological coping strategies, history of weight loss, muscle tissue maintenance, frequency of physical activity, presence of other life stressors and history of traumas. This means that weight loss is not a story of willpower- and for some people it will take more and different approaches than others. Making anyone feel like it’s their own psychological weakness they are facing these struggles is completely incorrect, and very psychologically harmful.

- Eating red meat and a few green vegetables is how we’re “supposed” to eat. There are a lot of different healthy diets, actually, and not all of them involve kale shakes. For example, the traditional diet of people native to Alaska is rich in fish, walrus, and whale fat, with very little access to round the year produce - and it’s a very heart-healthy diet. Similarly, there’s a lot of plant-only diets in various regions that are also incredibly healthy. Recent work shows that if you get enough protein overall, plant-based protein is just as beneficial as animal protein in terms of muscle building capacity. We shouldn’t halo foods without nuance. In general, less processed foods, more plant-and-whole foods based eating is good all around. If you have access to them, dark green vegetables are always a win.

- All or nothing thinking mixed with a misunderstanding of “effect size”, or how much a single bite of anything matters. The effect size on your health or weight of having some of your mom’s cookies or a packaged bar when you’re pressed for time is essentially non-existent, especially compared to the gain of social connection or reaching a deadline without passing out from hunger. Yes, small things add up over time - and that’s where regular behavioral self-monitoring and self-insight come into play. Look back and count how many times you had a cookie with your mom (is it once or every day?). Self-knowledge and self-compassion are both necessary to cultivate in this journey.

What do people (wrongly) think they need to do to lose weight vs. habits that are actually effective for weight loss?

People think going “all in” is the only effective way to kickstart their health journey (like meal prepping for an entire week or signing up to a two week bootcamp at the gym), but it’s often doing the opposite. Because it’s so different from usual routines, people are set up for failure. The best way to lose the right kind of weight and keep it off is much more manageable: consistency. Try small, new things and pick one to stick with for a week and watch how you feel. How does it work? How do you like it? How sustainable is it? Does it need tweaks? Try it consistently for another week. How did it go? Can you keep doing it for a month? A year? Then try another new thing. Lather, rinse, repeat. It’s not popular, but it doesn’t have to be boring.

What are some mistakes people make when trying to lose weight or areas where people are wasting their time and efforts?

Focusing on the number of pounds rather than the type of pounds. We should prioritize losing fat tissue, and preserving muscle. Tracking strength gains on a strength training program (e.g. increasing reps, weight, time under tension, sets) is a hack to ensure you are minimizing weight loss from muscle tissue.

On the other hand, not focusing on any outcome is also a mistake. Again, Michaela Kiernan’s work shows that weighing yourself every day helps give you an idea of:

1. How much your weight fluctuates on a daily basis regardless of actual fat weight changes.

2. If you are straying from your ultimate trajectory goal (losing fat).

It gives you a marker of real-time progress to allow for small self-corrections along the way. Just always pair it with strength training (yes, I have a serious bias towards promoting that in everyone).

What are some other methods to lose weight people might not have explored yet?

Self-hypnosis is a wonderful way to both aid in weight loss goals but also promote a cleaner, calmer, and more manageable internal space. It’s like cleaning out and organizing your personal psychological junk drawers, training the brain to focus for long periods of time, teaching you to be aware of our thoughts and self-dialogue. It’s incredibly helpful for not just weight loss but ANY life behavior change. You can DO all the things – but if your brain and heart can’t process the challenges of life or provide the self-compassion necessary for enjoying and thriving, the doing doesn’t really matter.

We do know that training ourselves to have sustained focus (like in various forms of meditation, endurance running or anything where your brain works to keep sustained attention) has impressive effects on stress, depression, and states of calm. This is another way hypnosis can work. The hypnosis helps build this muscle of sustained attention. It also helps direct it. Stopping the habitual self-talk we might have that gets in the way of our thriving. It’ll help fill in the well-worn ski paths down 'Thought Mountain' and hopefully carve some new runs that are more peaceful and have less boulders in the way.

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