Nutrition and weight: It’s personal


Even though we are all aware of the benefits of healthy eating, many of us still struggle to maintain a healthy weight while eating nutritious foods. Are some diets better than others? Do diets even work at all? Or do genetics determine outcomes regardless of what we eat?


To answer these and other questions about weight and nutrition, HealthySteps to Wellness spoke with Christopher Gardner, PhD, Rehnborg Farquhar Professor at the Stanford Prevention Research Center.

Metabolism and genetics play a role in weight, but your weight is mostly determined by your choices and food environment.

By various estimates, genetics play an approximate 30% role in determining our weight. Thus, factors other than  genetics are considerably more significant in determining weight.

“Most of your weight is determined by you and your food environment,” Gardner says.

Gardner notes that you can’t gain weight without eating more calories than you expend during the day, and you can’t lose weight without eating fewer calories than you expend. However, two people who eat the same amount of extra calories may gain different amounts of weight due to metabolic differences; and two people who restrict the same amount of calories my lose different amounts of weight due to those differences. (However, that difference is likely only a few pounds.)

No diet is best for all people, but the basics of a healthy diet are the same.

There are different diets, such as low-carb or low-fat diets, that are better for different people. There is no single diet that is best for overall health for everybody.

However, all healthy diets have these aspects in common:

  • High in vegetables
  • Mainly whole foods
  • Low or absent in added sugars and refined grains
  • Low or absent in processed foods

“After that, some people do better with lower-fat and higher-carb foods such as steel cut oats; while some people do better with higher-fat and lower-carb foods such as avocados,” Gardner states.

Gardner points to a weight loss study he conducted comparing healthy low-fat and healthy low-carb diets. The study participants in each diet were given a few ground rules:

  • Include lots of vegetables
  • Include as many whole foods and unprocessed foods as you can
  • Limit added sugar and refined grains, which are not satiating

Participants in the low-carb diet ate healthy fats — such as fatty fish and avocados, and participants in the low-fat diet ate healthy carbs — such as whole grains, beans and whole fruits. Participants were encouraged to find the lowest level of carbs or fat they could maintain so they didn’t feel hungry and could continue the diet for the duration of the study.

Study participants collectively lost  >6,000 pounds over 12 months, with each diet having about the same average weight loss. Interestingly, the participants were not given specific calorie restriction targets. Rather, they were instructed to avoid feeling hungry and deprived. Gardner theorizes that while genetic markers weren’t indicative of which diet worked best for which people, some people likely feel more satiated eating a healthy low-carb vs. a healthy low-fat diet, and that satiation leads to eating less calories.

“The overall goal still has to be a caloric restriction, but some calories are more nutritious and filling than others. In this world of personalization, get the foundational aspects of a healthy diet right. There will be a level of personalization after that and people would have to listen to their bodies to figure out what works.”

Make changes in your nutrition that you can keep.

Approximately 95% of people who go on a diet regain the weight they lost because eventually they go off the diet.

“The key is to not ‘go on a diet‘ but instead to change eating patterns forever,” Gardner says. “If while going on a weight loss diet you are making changes that you won’t be able to maintain for the rest of your life, then you are probably taking an ineffective approach.”

There are many approaches that promise quick weight loss with little time invested. However, if you’re taking an approach that’s intended to be transient, then the subsequent health benefits and weight loss will likely be transient, too.

Set a SMART goal to change your eating habits.

A SMART goal — Specific, Measurable, Attainable, Realistic and Timely — can help you improve your eating habits. Gardner suggests asking yourself these questions:

  • What are the specific things you eat or drink that you think most undermine your nutrition goals?
  • Among those, which one(s) is/are you most willing to try to change.

“Start with the one thing that you’re most willing to work on, and the most likely to succeed with. If you change everything at the same time, you may get overwhelmed and feel like you can’t make the changes you want to make.”

For example, if you want to start eating more vegetables, you can make a SMART goal that you’ll have grilled vegetables with three of your dinners that week. Then, at the end of the week, count up. How did you do? All three? Great! Applaud yourself for meeting your goal. Just one or two but not three? Ask yourself why. Try again, or choose a different SMART goal. The same is true for something you want to reduce in your diet. Set a SMART goal for consuming it less than you currently are and gradually set new goals over time until you’ve made the desired change.

Find your inner motivator.

Gardner notes that it takes a month to make a new habit, and he suggests trying different things to see what motivates you to maintain your changes, which he dubs “seeking your inner motivator.”

A lot of people focus on feeling better now. Gardner recounts that through his work at the Stanford Prevention Research Center (SPRC) and The WELL Initiative, people who improved their diets reported feeling better, having more energy and enjoying life more — immediately, even before there was a substantial change on the weight scale.

 Another motivator may be considering the societal and environmental costs of your food choices. Gardner mentions that the foods that are best for you are also best for the planet. You can reinforce your healthy eating by thinking about the positive societal and environmental effects of your eating choices. He cites a study he conducted that shows an increase in reported healthy eating behaviors after students took a course on societal-level issues related to food and food production.

Address the barriers keeping you from making healthy food choices:
Time, money and taste.

Time, money and taste are some of the most commonly cited barriers to making nutritious eating choices. Gardner encourages you to examine your personal situation and find hacks to make healthy choices sustainable. For example, if you’re low on time, he suggests buying pre-prepared frozen vegetables, which usually have comparable nutritional value as fresh vegetables.

If money is a barrier, he notes that produce is cheaper if you buy what’s in season; grains and beans are less expensive than other foods, particularly when you buy in bulk; and there’s no nutritional need to focus on organic and high-end grocery stores. He also promotes the idea of grain and bean bowls, which have become popular and which you can personalize to your taste preferences.

Gardner discusses that an unfortunate and inappropriate false dichotomy has developed around the idea that you can either eat flavorful foods or healthy foods but not foods that are both. He cites a multi-disciplinary study he collaborated on that was led by Stanford psychology professor, Alia Crum, and her graduate student Brad Turnwalk. Conducted across Stanford and four other universities, the study found that vegetables labeled with taste-focused names, such as “sizzlin’ Szechuan green beans with toasted garlic,” were picked far more than and considered to taste better than the same vegetables labeled with health-focused names, such as “nutritious green beans.” To consider healthy food flavorful, you may have to change your mindset on how delicious vegetables can be; Gardner suggests you  experiment with different cooking approaches to find out what works for you.

Stanford is working to make nutritious foods more accessible.

Stanford collaborates with The Culinary Institute of America to lead The Menus of Change University Research Collaborative (MCURC), which promotes healthy eating choices at universities. There are currently ~60 member universities. MCURC works with chefs and public health experts to create delicious, nutritious dishes available at university dining facilities.

Gardner touts how across all seven schools at Stanford, there are faculty and students interested in the food system, and these experts can collaborate to find an interdisciplinary approach to improve the system.

“Stanford is a great place to find solutions to system level problems and challenges.”

By Katie Shumake
January 2020