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Weight Loss And Plant-Based Diets

Updated: Jul 12, 2023

Managing and sustaining a healthy body weight can be challenging. There’s a reason why the diet industry has been estimated to be worth over 200 billion dollars in 2019.

With the ever increasing rates of overweight and obesity, now affecting almost 2/3 of North Americans, it’s estimated that the diet industry will grow to over 300 billion dollars by 2027. If meds really cured disease, then you wouldn’t require refills, and the same goes for diets. By definition, diets are temporary and are rarely compatible with long term and sustainable lifestyle change. Long term benefits require long term lifestyle change. How does the plant-based diet fit in our obesogenic environment?

Recently, I received a message from a curious reader who was hesitant to include oatmeal in her routine due to its caloric content and density. Remember that populations who regularly consume whole grains are among the longest living populations on Earth, with the lowest rates of chronic diseases. After reading her message, I was a little confused, since plants have much lower caloric density than most processed foods and animal products. I then realized that if she had this concern, she probably wasn't the only one. When talking about weight loss, there are many concepts to cover, and so I’ll try to simplify them and make them as clear and concise as possible.

Among the concepts that will require some clearing up, we have:

  • the obesogenic environment

  • the weight loss laws of thermodynamics

  • calorie density

  • a calorie isn’t always a calorie

  • the microbiome and weight management

  • properly reading nutritional labels

Also, "plant-based diet" is an umbrella term. It includes plant-forward diets like the Mediterranean diet, the Portfolio diet, the DASH diet as well as flexitarianism, vegetarianism and veganism. If your first gut instinct is "I could never go full plant-based" then you don't have to. Any step in the right direction and towards more plants on your plate will get you closer to better health.

Our Obesogenic Environment

This one is easy to summarize. Our biology has evolved in an environment of scarcity over millions of years. Over the last century, which accounts for a mere fraction of a second relative to the timescale of our existence, we have had an industrial revolution, where we’ve developed technology that has helped us store, cook and preserve food. Many types of food processing methods, like pickling, jarring or freezing, don’t necessarily modify food chemistry and aren't inherently bad at all. Since there is a downside to all technological advancements, our desire to push tech forward has led to clever ways to produce food to feed the masses, often to the detriment of our health. Food processing has helped us make calories more concentrated, less satiating and highly palatable. Modern fast foods hijack our senses of taste, smell and mouthfeel and Mother Nature just can’t compete with that. Our biology is simply not equipped to survive in an environment of abundance and hyper palatable-foods. Processed foods alone can’t explain our obesity trends, but do account for a large part. This subject is a complex one, with many nuances which deserves its very own article. Just so happens that I’ve already written a thorough review of the obesity pandemic. You can read it here.

The Laws Of Thermodynamics

Weight gain can be summed up as the relationship between the calories you ingest and those you burn. Calories in minus calories out will result in a positive calorie balance that will lead to weight gain over time, or weight loss if your calorie balance is negative. The "calories in" part of the equation is pretty simple and is limited to the calories you consume. The "calories out" part of the equation is a little more complex and includes your BMR (basal metabolic rate) which is the amount of calories you burn just for basic organ function. It also includes the calories you burn during exercise (exercise induced thermogenesis) and NEAT (or non-exercise activity thermogenesis), which is the calories burned just by walking to your car for example. The last part of the calories out equation includes the calories required to digest, absorb and process the foods you eat. This phenomenon, called food thermogenesis is not insignificant since it requires more calories to burn off protein than it does to burn off fat. Although oversimplified, you can‘t avoid the basic laws of thermodynamics, and in a nutshell (although there are small nuances):

Calorie Balance = Calories In - Calories Out

This concept is so important that I also have an entire article dedicated to the calorie balance equation. You can read it here!

Calorie Density

This important concept describes the amount of calories per amount of food and is often described as calories found in a specific weight of food. Many studies have found that most people eat between 3-4 pounds of food, regardless of the type, and food ingestion seems to depend more on weight and size than on calorie content. This means that people who eat 3 pounds of calorie dense foods will ingest much more total calories than someone who eats the same 3 pounds of foods that have a low calorie density. This is one of the things that make plant-based diets shine. In general, most plant foods will have a much lower calorie density that processed or animal based foods.

Careful calculations from experts in the field have determined this as the basic formula for weight loss: weight maintenance will occur for the average person at an average calorie density of 125 calories per 100 grams of food. This translates to about 570 calories per pound of consumed food. So, no matter what foods you eat, the general rule is that as long as the average calorie density of what you’re eating is less than 125 calories per 100 grams, or 570 calories per pound, then you should be maintaining a stable body weight. You can choose to do one of two things to lose weight, considering that your activity level and NEAT (you can read about NEAT here) remain the same. You can aim to 1) eat the same amount or volume of food, but eat lower calorie dense foods or 2) eat less foods in total by not changing the calorie density of you meals, but simply eating smaller meal portions. Personally, I’d choose 1). Eating more food until I’m satisfied aligns better with who I am.

If this sounds too complicated, then you can check nutrition labels (learn how to read them here) or you can google the calorie density of the food by searching for the number of calories in 100 grams of food. A quick google search will give you that information. Remember that some super healthy foods, like grains and nuts, will have higher calories densities. I can‘t stress this enough: it‘s the average calorie density of your diet that counts. Use higher calorie dense foods judiciously. This doesn’t mean they’re off limits. If the food you’re looking for has less than 125 calories per 100 grams of food (or 570 calories per pound), then it‘s likely to help support weight loss. Since fullness is mainly determined by stretch receptors in our stomachs, eating foods containing less than 125 calories per 100 grams, like fruits and veggies, will make you feel much fuller than 125 calories of olive oil or meat, which will not take up much space in a stomach than can accommodate up to 900 milliliters of food. These two foods contain the same amount of calories, but have much different abilities to make us feel satisfied and full. Check out the graph below. If you can keep most of your meals at an average calorie density of less than 125 calories per 100 grams, you’re very likely to lose weight over time. If you choose to regularly consume foods that have more than 570 calories per pound, you know, because you want to, then you have to be careful with portion sizes, since satiety signals from your stomach won't be able to help you much. In terms of weight loss, this doesn't mean that you have to avoid anything that has more than 570 calories per pound. It simply means that you will have to rely on other cues than your satiety signals, especially if you're consuming processed foods. These have the innate ability to be consumed in large quantities without triggering your fullness cues.

Understanding the concept of calorie density and using it to your advantage will help those who have felt hungry or unsatisfied on restrictive diets. We have studies where people consuming plant-based diets were eating until they were full (also called eating "ad libitum"), and still managed to lose weight, simply because the foods they were eating were lower in calorie density. Most diets cause weight loss through caloric restriction, and if you're not restricting calorie dense processed or animal based foods, then you will have no choice but to eat less food and smaller portions in terms of volume and weight in order to achieve weight loss. The laws of thermodynamics and physics aren't going to change. When people say: "I've been eating in a calorie deficit for weeks and haven't lost weight", I feel bad to break it to them, but they're not in a calorie deficit at all. We have great studies, including metabolic ward studies, where every single calorie was tracked. These studies always come to the same conclusion: humans are very bad at tracking total calories. No human can escape the laws of nature. If you're not losing weight, then you're not in a calorie deficit. Period. If your diet consists of very calorie dense processed foods, the only way to lose weight while continuing to eat these foods will be to limit portion sizes, meaning that you‘ll be highly likely to experience hunger and lack of satisfaction or fullness after meals. This makes it next to impossible to maintain over time.

Plant-based diets have proven there worth as disease fighters and preventers. Water and fiber in plants add bulk and weight, without adding calories, effectively diluting calories and making foods more filling, without added calories. Unfortunately, some types of food processing removes fiber and water to make the food more shelf stable. This process concentrates calories in a smaller, less filling volume. No wonder those consuming highly processed food are left hungry and unsatisfied. Even after millions of years of evolution, we still use basic stretch receptors in our stomachs as the main mechanism to determine if we’re ready to stop eating or not. A distended stomach can fit about 900 ml, or a little less than 4 cups of food. If it‘s filled with foods low in calorie density, like plants, you might have 300-500 calories in a stomach full, whereas the same amount of food from animal based or processed foods might add up to well over a thousand calories. Without fiber, all of these calories will get absorbed quickly, leaving you hungry in no time, whereas fiber in plants slows down digestion and gastrointestinal transit time, and provides bulk that may keep you full for hours.

It's also super important to keep in mind that some of the healthiest foods in the world can have high calorie densities. Nuts, seeds, avocados and even legumes have more than 570 calories per pound. Should you be avoiding these foods, or should you be more careful with them? Just so happens that these foods, even considering their calorie density, are packed with fiber, and eating these foods in their unprocessed forms has a huge impact on creating fullness and limiting excess calorie intake later in the day. Hunger and appetite are complex neuro-hormonal processes, but studies have repeatedly shown that those who eat more legumes, nuts and seeds, even considering their higher calorie densities, have healthy body weights and are less likely to overeat. Calories in versus calories out is a huge predictor of weight gain or loss, but many nuances exist and eating calorie dense whole foods triggers a strong satiety response that prevents excess calorie intake later in the day. Don't believe me? Check out this blog post where I deep dive in the how fiber does much more than just regulate bowel function (here) and you might want to read this one where I explain the science of why "A Calorie Isn't Always A Calorie".

A Calorie Isn’t Always A Calorie

Although many still don’t buy it, the science is clear on this. Eating 250 calories worth of chocolate will not impact your body and weight in the same way as 250 calories of carrots. Again, a 1000 calorie salad will not impact your weight in the same way as a 1000 calorie BigMac Combo. Many people hate hearing this, but let me explain in further detail. It’s not the calories you eat that matters, but the ones you absorb. Everyone has noticed some blueberries or bits of corn in their stool after devouring corn on the cob. Plant foods contain fiber, and that means that macroscopic particles that go undigested, like the pieces of corn in the toilet, are flushed down the toilet and not absorbed. The same thing goes for smaller microscopic particles of food. Undigested fiber from plants, even if microscopic, traps calories that pass untouched through your digestive system and get flushed down the toilet. Calories from processed foods, where the fiber has been traded for shelf life and taste, or animal products, that contain zero fiber, can be released much easier and absorbed freely. If you consume 500 calories of a sugary soda, then all 500 are easily and quickly absorbed. The same 500 calories of corn won‘t get absorbed completely, since large and microscopic pieces will go right through your digestive system without being released from fiber, getting flushed down the toilet instead of ending up in your hips. That‘s not the only way plant foods are magical. After consuming 500 calories of beans, the fiber content will keep you fuller for longer and will slow down digestion and limit calorie consumption between meals, whereas 500 calories of fast food will get digested and absorbed super quickly, leaving you hungry and craving for more within a few short hours.

The Microbiome

We are just beginning to learn how the microbiome can affect weight gain and it‘s fascinating. When you consume fiber rich plants, your gut bugs ferment that fiber and produce post-biotics in return. These chemical compounds, called SCFA (short chain fatty acids) get absorbed in your circulation and make it to almost every organ in your body. It tells your digestive system to slow digestion, leaving you fuller for longer. It crosses the blood brain barrier and decreases appetite. Other metabolites found in plants, like polyphenols, have similar effects. An interesting study that was done in rats sheds a light on the potential impact of the microbiome on obesity. Check out this cool experiment! Lab mice born in sterile conditions without a microbiome were given fecal transplants from obese mice. Another group of sterile mice was given a fecal transplant from thin mice. The mice who got the obese mice’s microbiome became obese, and the other mice did not, even after being put on a calorie equivalent diet. Now if that doesn’t defy expectations, I don’t know what will. Both groups had access to identical calories, yet the only factor that seemed to impact weight gain was their microbiome. This study was pivotal in understanding how calorie intake is only a part of the explanation. It is now well accepted and proven that those suffering from obesity have different microbiomes than those who don’t. Just by looking at stool samples, experts can even tell if the sample came from an obese or normal weight individual. Although more research needs to be done, studies like these have clearly indicated that there’s more to the picture than just calories in and calories out. You can read more about our microbiome and how it affects our health here.

Nutritional Labels

The healthiest foods don’t have labels or ingredients. Choose foods that have the shortest ingredients list and don’t rely solely on calorie content to make your purchasing decisions. Most people look for low calorie processed crap that is devoid of fiber and reeks havoc on their microbiome. Not to mention the additives and preservatives and chemically complex ingredients that negatively affect our health. I don’t look at calories on nutritional labels, I look at ingredients, choose minimally processed foods as much as I can and look for foods that don’t require labels. Many will glance at labels and get intimidated by macros, like the amount of fat or carbs, not questioning whether those grams of fat are from saturated or unsaturated sources. Some get scared of high carb containing foods, unaware that fiber is a source of carbs that contains zero calories, or that complex carbs aren’t metabolically equivalent to simple carbs or sugars. I wrote a blog specifically for those wanting to learn more about reading nutrition labels, since most only look at total calories or fat, when this is just a small piece of the bigger picture. You can read it here.

Processed Plant Foods

Just because it's plant-based doesn’t mean it’s healthy. We have lots of plant-based processed crap on the market today with very long lists of ingredients. Some of them do serve as great stepping stone foods for those looking to transition away from animal products and many of them have helped me greatly on my transitional journey. But that doesn’t mean it ends there. I started off with plant-based fake meats, and Beyond Meat burgers and Impossible Burgers did play a major role in transitioning towards less processed foods. Now, I enjoy making our own whole food burgers out of lentils and chickpeas or walnuts and beans. These foods can all be compatible with your journey of plant-based eating while maintaining a calorie deficit.

Calorie Dense Plants

When thinking about calorie dense plant foods, one must not forget that excess calories will result in weight gain, no matter their source. Even though plants come packaged with fiber and phytonutrients that are protective against weight gain, you can still gain weight while overconsuming them. The main culprits in terms of plant-based foods to watch out for are oils. Whether it‘s olive oil or flaxseed oil, they’re still highly processed and extremely calorie dense. In terms of unprocessed whole foods, be careful with avocados, olives, nuts and seeds, including nut and seed butters. Although these foods are extremely health promoting, they are only when consumed as part of a calorically adequate diet. For those just starting on their weight loss journey, limiting these foods is reasonable, but definitely try to find the nutrients they contain in other less calorie dense sources. Also be reassured that studies on calorie dense whole plants show the opposite of weight gain. Although counter-intuitive, eating more calorie dense unprocessed plants has been shown to dramatically decrease appetite and prevent excessive calorie intake later in the day. Nut consumption for example, a calorie dense plant, is associated with lower body weight, improved longevity and reduced rates of chronic diseases. If you're still worried and remain skeptic even with the overwhelming science showing no increase in weight in those consuming nuts, once your weight has stabilized, definitely try to include a variety of these foods. They are associated with longevity and reduced rates of chronic disease.

My Weight Management Conclusion

If you're looking to lose weight, you have 2 choices. Either you can eat less food or you can choose to eat the same amount of food, but lower in calorie density. You can always try to burn more calories simply by trying to out-exercise a bad diet, but studies have repeatedly shown that this is highly ineffective and unsustainable. That being said, achieving a healthy body weight is easier said than done, and connecting to "why" you want to do it is much more important than "how", in sustaining weight loss over the long term. If you know you have to lose weight, and you already know how, but still are struggling to make it happen, you might want to read this recent blog post about the process of change. Doctors are great at giving you factual knowledge about vitamins and minerals and calories, but changing your mindset and repairing your relationship with food is not our "forte" or expertise. If you're looking for help in this area, I strongly suggest you take a look at what these two wonderful humans have to offer. Josée and Alicia at "Your Way Weight Loss" walk the walk and talk the talk. They've documented their weight loss journeys for years and have created a tight community of followers that support each other by talking about the mindset factors that keep most people from achieving their goals. Repairing the relationship people have with food is at the heart of the weight loss process. Even with all the knowledge in the world, it's still possible to struggle with achieving a healthy body weight, a healthy self-esteem and a healthy self-image. That's where Your Way Weight Loss comes in.

Many people starting on plant-based diets will actually lose weight involuntarily since the foods they consume are so calorie poor. Many even complain of fatigue since they’re falling way short of their daily calorie requirements. It’s funny how people think that those on plant-based diets are always starving when it’s literally the opposite that happens. I haven’t counted calories in years and simply eat intuitively. If I’m hungry, I eat. When I’m not I don’t. I don’t envy those that are weighing their foods, measuring portions and counting calories, although I do understand that these practices are absolutely necessary for some when trying to lose weight while eating processed and calorie dense foods. Studies clearly show that those on unprocessed plant-based diets can eat more food and still lose weight while feeling fully satisfied after meals. That being said, the plant-based lifestyle is something that you have to want to do. There are countless and infinite ways to make whole foods taste good, but if you'd rather have convenience, fast-foods and chronic disease, you’re probably on the wrong website. Plant-based diets do require some motivation and planning, but they aren’t black and white or all or nothing. Try meatless Mondays or tofu Thursday. Drink more smoothies and throw some kale or spinach in there and use plant-based milks instead of cow’s milk. Switch your eggs and bacon for oatmeal and fruit here and there. You’ll reap the benefits of what you put in. If you do plant-based meals 20% of the time, then you’ll likely be 20% healthier and lose a few pounds effortlessly along the way. Don’t let being perfect get in the way of being better.

Check out my website and look for the « For Weight Loss » in the menu. Also look for the “How To” section in the menu. There, you’ll find tips and tricks that helped me on my journey towards a plant-predominant diet. Everything there is completely free, no catches! If you're looking for quick, easy and healthy plant-based recipes, check out and download my free recipe eBook!

Look for me on the socials, @plantbased_dr_jules on Instagram and go like my Facebook Page, Plant-based Dr. Jules. If you’re looking for some fitness motivation and are curious to see what a plant-based athlete can accomplish, follow me, @maritimeninja, on my fitness account on Instagram or check out my fitness group on Facebook, called Maritime Ninja Warrior. I'm a two-time world championship qualified athlete and you can follow my fitness journey there! You can even access the resources section by becoming a member. It's free and there, you can download free resources like my plant-based recipe eBook!

You also check out my YouTube channel here for more tips and tricks on how to embark on a plant-based journey!

Thanks so much for reading! Please consider sharing this article!

Plant-Based Dr. Jules 💚🌱

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