vegetable protein

Can Healthy Eating Help You Lose Weight?

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Who Benefits Most From A Healthy Diet?

Author: Dr. Stephen Chaney 

fad dietsFad diets abound. High protein, low carb, low fat, vegan, keto, paleo – the list is endless. They all claim to be backed by scientific studies showing that you lose weight, lower your cholesterol and triglycerides, lower your blood pressure, and smooth out your blood sugar swings.

They all claim to be the best. But any reasonable person knows they can’t all be the best. Someone must be lying.

My take on this is that fad diet proponents are relying on “smoke and mirrors” to make their diet look like the best. I have written about this before, but here is a brief synopsis:

  • They compare their diet with the typical American diet.
    • Anything looks good compared to the typical American diet.
    • Instead, they should be comparing their diet with other weight loss diets. That is the only way we can learn which diet is best.
  • They are all restrictive diets.
    • Any restrictive diet will cause you to eat fewer calories and to lose weight.
    • As little as 5% weight loss results in lower cholesterol & triglycerides, lower blood pressure, and better control of blood sugar levels.

Simply put, any restrictive diet will give you short-term weight loss and improvement in blood parameters linked to heart disease, stroke, and diabetes. But are these diets healthy long term? For some of them, the answer is a clear no. Others are unlikely to be healthy but have not been studied long term. So, we don’t know whether they are healthy or not.

What if you started from the opposite perspective? Instead of asking, “Is a diet that helps you lose weight healthy long term?”, what if you asked, “Can healthy eating help you lose weight?” The study (S Schutte et al, American Journal of Clinical Nutrition, 115: 1-18, 2022) I will review this week asked that question.

More importantly, it was an excellent study. It compared a healthy diet to an unhealthy diet with exactly the same degree of caloric restriction. And it compared both diets to the habitual diet of people in that area. This study was performed in the Netherlands, so both weight loss diets were compared to the habitual Dutch diet.

How Was The Study Done?

clinical studyThis was a randomized controlled trial, the gold standard of clinical studies. The investigators recruited 100 healthy, abdominally obese men and women aged 40-70. At the time of entry into the study none of the participants:

  • Had diabetes.
  • Smoked
  • Had a diagnosed medical condition.
  • Were on a medication that interfered with blood sugar control.
  • Were on a vegetarian diet.

The participants were randomly assigned to:

  • A high-nutrient quality diet that restricted calories by 25%.
  • A low-nutrient-quality diet that restricted calories by 25%.
  • Continue with their habitual diet.

The study lasted 12 weeks. The participants met with a dietitian on a weekly basis. The dietitian gave them the foods for the next week and monitored their adherence to their assigned diet. They were advised not to change their exercise regimen during the study.

At the beginning and end of the study the participants were weighed, and cholesterol, triglycerides, and blood pressure were measured.

Can Healthy Eating Help You Lose Weight?

Vegetarian DietTo put this study into context, these were not healthy and unhealthy diets in the traditional sense.

  • Both were whole food diets.
  • Both included fruits, vegetables, low-fat dairy, and lean meats.
  • Both restricted calories by 25%.

The diets were designed so that the “high-nutrient quality” diet had significantly more plant protein (in the form of soy protein), fiber, healthy fats (monounsaturated and omega-3 fats), and significantly less fructose and other simple sugars than the “low-nutrient-quality” diet.

At the end of 12 weeks:

  • Participants lost significant weight on both calorie-restricted diets compared to the group that continued to eat their habitual diet.
    • That is not surprising. Any diet that successfully restricts calories will result in weight loss.
  • Participants on the high-nutrient quality diet lost 33% more weight than participants on the low-nutrient-quality diet (18.5 pounds compared to 13.9 pounds).
  • Participants on the high-nutrient quality diet lost 50% more inches in waist circumference than participants on the low-nutrient-quality diet (1.8 inches compared to 1.2 inches).
    • This is a direct measure of abdominal obesity.

When the investigators measured blood pressure, fasting total cholesterol levels, and triglyceride levels:Heart Healthy Diet

  • These cardiovascular risk factors were significantly improved on both diets.
    • Again, this would be expected. Any diet that causes weight loss results in an improvement in these parameters.
  • The reduction in total serum cholesterol was 2.5-fold greater and the reduction in triglycerides was 2-fold greater in the high-nutrient quality diet group than in the low-nutrient-quality diet group.
  • The reduction in systolic blood pressure was 2-fold greater and the reduction in diastolic blood pressure was 1.67-fold greater in the high-nutrient quality diet group than in the low-nutrient-quality diet group.

The authors concluded, “Our results demonstrate that the nutrient composition of an energy-restricted diet is of great importance for improvements of metabolic health in an overweight, middle-aged population. A high-nutrient quality energy-restricted diet enriched with soy protein, fiber, monounsaturated fats, omega-3 fats, and reduced in fructose provided additional health benefits over a low-nutrient quality energy-restricted diet, resulting in greater weight loss…and promoting an antiatherogenic blood lipid profile.”

In short, participants in this study lost more weight and had a better improvement in risk factors for heart disease on a high-nutrient-quality diet than on a low-nutrient-quality diet. Put another way, healthy eating helped them lose weight and improved their health.

Who Benefits Most From A Healthy Diet?

None of the participants in this study had been diagnosed with diabetes when the study began. However, all of them were middle-aged, overweight, and had abdominal obesity. That means many of them likely had some degree of insulin resistance.

Because of some complex metabolic studies that I did not describe, the investigators suspected that insulin resistance might influence the relative effectiveness of the two energy-restricted diets.

To test this hypothesis, they used an assay called HOMA-IR (homeostatic model assessment of insulin resistance). Simply put, this assay measures how much insulin is required to keep your blood sugar under control.

They used a HOMA-IR score of 2.5 to categorize insulin resistance among the participants.

  • Participants with a HOMA-IR score >2.5 were categorized as insulin-resistant. This was 55% of the participants.
  • Participants with a HOMA-IR score ≤2.5 were categorized as insulin-sensitive. This was 45% of the participants.

When they used this method to categorize participants they found:

  • Insulin-resistant individual lost about the same amount of weight on both diets.
  • Insulin-sensitive individuals lost 66% more weight on the high-nutrient-quality diet than the low-nutrient-quality diet (21.6 pounds compared to 13.0 pounds).

The investigators concluded, “Overweight, insulin-sensitive subjects may benefit more from a high- than a low-nutrient-quality energy-restricted diet with respect to weight loss…”

What Does This Study Mean For You?

Questioning WomanSimply put this study confirms that:

  • Caloric restriction leads to weight loss, and…
  • Weight loss leads to improvement in cardiovascular risk factors like total cholesterol, triglycerides, and blood pressure.
    • This is not new.
    • This is true for any diet that results in caloric restriction.

This study breaks new ground in that a high-nutrient quality diet results in significantly better:

  • Weight loss and…
  • Reduction in cardiovascular risk factors…

…than a low-nutrient quality diet. As I said above, the distinction between a “high-nutrient-quality” diet and a “low-nutrient-quality” diet may not be what you might have expected.

  • Both diets were whole food diets. Neither diet allowed sodas, sweets, and highly processed foods.
  • Both included fruits, vegetables, grains, and lean meats.
  • Both reduced caloric intake by 25%.
    • If you want to get the most out of your weight loss diet, this is a good place to start.

In this study the investigators designed their “high-nutrient-quality” diet so that it contained:

  • More plant protein in the form of soy protein.
    • In this study they did not reduce the amount of animal protein in the “high-nutrient-quality” diet. They simply added soy protein foods to the diet. I would recommend substituting soy protein for some of the animal protein in the diet.
  • More fiber.
    • The additional fiber came from substituting whole grain breads and brown rice for refined grain breads and white rice, adding soy protein foods, and adding an additional serving of fruit.
  • More healthy fats (monounsaturated and omega-3 fats).
    • The additional omega-3s came from adding a fish oil capsule providing 700mg of EPA and DHA.
  • Less simple sugars. While this study focused on fructose, their high-nutrient-quality diet was lower in all simple sugars.

ProfessorAll these changes make great sense if you are trying to lose weight. I would distill them into these 7 recommendations.

  • Follow a whole food diet. Avoid sodas, sweets, and highly processed foods.
  • Include all 5 food groups in your weight loss diet. Fruits, vegetables, whole grains, dairy, and lean proteins all play an important role in your long-term health.
  • Eat a primarily plant-based diet. My recommendation is to substitute plant proteins for at least half of your high-fat animal proteins. And this study reminds us that soy protein foods are a convenient and effective way to achieve this goal.
  • Eat a diet high in natural fibers. Including fruits, vegetables, whole grains, beans, nuts, seeds, and soy foods in your diet is the best way to achieve this goal.
  • Substitute healthy fats (monounsaturated and omega-3 fats) for unhealthy fats (saturated and trans fats) in your diet. And this study reminds us that it is hard to get enough omega-3s in your diet without an omega-3 supplement.
  • Reduce the amount of added sugar, especially fructose, from your diet. That is best achieved by eliminating sodas, sweets, and highly processed foods from the diet. I should add that fructose in fruits and some healthy foods is not a problem. For more information on that topic, I refer you to a previous “Health Tips” article .
  • Finally, I would like to remind you of the obvious. No diet, no matter how healthy, will help you lose weight unless you cut back on calories. Fad diets achieve that by restricting the foods you can eat. In the case of a healthy diet, the best way to do it is to cut back on portion sizes and choose foods with low caloric density.

I should touch briefly on the third major conclusion of this study, namely that the “high-nutrient quality diet” was not more effective than the “low-nutrient-quality” diet for people who were insulin resistant. In one sense, this was not news. Previous studies have suggested that insulin-resistant individuals have more difficulty losing weight. That’s the bad news.

However, there was a silver lining to this finding as well:

  • Only around half of the overweight, abdominally obese adults in this study were highly insulin resistant.
    • That means there is a ~50% chance that you will lose more weight on a healthy diet.
  • Because both diets restricted calories by 25%, insulin-resistant individuals lost weight on both diets.
    • That means you can lose weight on any diet that successfully reduces your caloric intake. That’s the good news.
    • However, my recommendation would still be to choose a high-nutrient quality diet that is designed to reduce caloric intake, because that diet is more likely to be healthy long term.

The Bottom Line 

A recent study asked, “Can healthy eating help you lose weight?” This study was a randomized controlled study, the gold standard of clinical studies. The participants were randomly assigned to:

  • A high-nutrient quality diet that restricted calories by 25%.
  • A low-nutrient-quality diet that restricted calories by 25%.
  • Continue with their habitual diet.

These were not healthy and unhealthy diets in the traditional sense.

  • Both were whole food diets.
  • Both included fruits, vegetables, low-fat dairy, and lean meats.
  • Both restricted calories by 25%.

The diets were designed so that the “high-nutrient quality” diet had significantly more plant protein (in the form of soy protein), fiber, healthy fats (monounsaturated and omega-3 fats), and significantly less fructose and other simple sugars than the “low-nutrient-quality” diet.

At the end of 12 weeks:

  • Participants on the high-nutrient quality diet lost 33% more weight than participants on the low-nutrient-quality diet (18.5 pounds compared to 13.9 pounds).

When the investigators measured cardiovascular risk factors at the end of 12 weeks:

  • The reduction in total serum cholesterol was 2.5-fold greater and the reduction in triglycerides was 2-fold greater in the high-nutrient quality diet group than in the low-nutrient-quality diet group.
  • The reduction in systolic blood pressure was 2-fold greater and the reduction in diastolic blood pressure was 1.67-fold greater in the high-nutrient quality diet group than in the low-nutrient-quality diet group.

The authors concluded, “Our results demonstrate that the nutrient composition of an energy-restricted diet is of great importance for improvements of metabolic health in an overweight, middle-aged population. A high-nutrient quality energy-restricted diet enriched with soy protein, fiber, monounsaturated fats, omega-3 fats, and reduced in fructose provided additional health benefits over a low-nutrient quality energy-restricted diet, resulting in greater weight loss…and promoting an antiatherogenic blood lipid profile.”

In short, participants in this study lost more weight and had a better improvement in risk factors for heart disease on a high-nutrient-quality diet than on a low-nutrient-quality diet. Put another way, healthy eating helped them lose weight and improved their health.

For more details on this study, what this study means for you, and my 7 recommendations for a healthy weight loss diet, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.

Do High Protein Diets Cause Cancer?

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How Much Protein Should We Eat?

Author: Dr. Stephen Chaney

Animal Protein FoodsThe recent headlines suggesting that high protein diets may cause cancer, diabetes and premature death in middle aged Americans are downright scary. You are probably asking yourself:

  • “Is this new information?”
  • “Does this apply to me?”
  • “Should I radically change what I eat?”

In this issue of “Health Tips From the Professor” I will address each of these questions.

Do High Protein Diets Cause Cancer?

The study in question (Levine et al., Cell Metabolism, 19: 407-417, 2014) suggested that high protein diets were associated with increased risk of cancer, diabetes and premature death in Americans in the 50-65 age range. I will touch on all three of these observations, but it is the increased risk of cancer that generated the most headlines – and the most concern (The consequences of diabetes take years to manifest, and death seem to be a more distant concern for most people. Cancer is immediate and personal).

The study looked at 6,381 adults aged 50 and older (average age 65) from the NHANES III data base. (NHANES is a comprehensive database collected by the Centers for Disease Control and Prevention that consists of surveys and physical examinations and is designed to be representative of the health and nutritional status of the US population.)

The data collected consisted of a single diet questionnaire conducted when the subjects were enrolled in the study. Based on the diet questionnaire the authors of the study divided the group into those with low protein intake (<10% of calories), those with moderate protein intake (10-19% of calories) and those with high protein intake (>20% of calories). Overall death and mortality from various diseases over the next 18 years was obtained by linking the NHANES data with the National Death Index.

Based on preliminary data suggesting that the age of the population might influence the results (I won’t go into details here) the authors of the study decided to subdivide the dataset into people aged 50-65 and people over 65. When they did that, they came to the following conclusions:

1)     In the 50-65 age group diets high in animal protein were associated with a:

  • 45% increase in overall mortality
  • 4-fold increase in cancer death risk
  • 4-fold increase in diabetes death risk.

Diets with moderate protein intake were associated with intermediate increases in risk. Surprisingly, there was no increase in cardiovascular disease risk.

Protein Shakes2)     When they looked at people in the 50-65 age group consuming diets high in vegetable protein:

  • the increased overall mortality and increased in cancer mortality disappeared
  • the increased diabetes mortality was still seen.

3)     In the 65+ age group high protein diets were associated with a:

  • 28% decrease in overall mortality
  • 60% decrease in cancer mortality.

The increased risk of diabetes related deaths was still observed. The authors did not distinguish between animal and vegetable protein in the over 65 age group.

All of that may seem to be a bit too complicated. At the risk of gross oversimplification I would summarize their message as follows:

  • Diets high in animal protein may be bad for you if you are in the 50-65 age range, but might actually be good for you if you are over 65.
  • Diets high in vegetable protein appear to be good for anyone over age 50 (The study didn’t look at younger age groups).

Is This New Information?

Let’s start by assuming that the conclusions of the authors are correct (more about that below).

When you boil their message down to its simplest components, the information isn’t particularly novel.

  • The idea that vegetable proteins may be better for you than animal proteins has been around for decades. There are a number of studies suggesting that diets high in animal protein increase the risk of cancer, heart disease, diabetes and overall death – although it is still not clear whether it is the animal protein itself or some other characteristic of populations consuming mostly animal protein that is the culprit.
  • Evidence has been accumulating over the past decade or so that protein needs increase as we age, so it is not surprising that this study found high protein diets to be beneficial for those of us over age 65.

What Do Other Experts Say?

ScientistSince this study has been released it has been roundly criticized by other experts in the field. Let me sum up their four main criticisms and add one of my own.

1)     The protein intake data were based on a single dietary survey taken at the beginning of an 18 year study. The authors stated that a single dietary survey has been shown to be a pretty accurate indicator of what an individual is eating at the time of the survey. However, it is problematic to assume that everyone’s diet remained the same over an 18 year period.

2)     The choice of less than 10% of calories from protein is also problematic. According to the Institute of Medicine standards anything below 10% is defined as inadequate protein intake, which can have long term health consequences of its own.

More importantly, only 7% of the population being studied (437 individuals) fell into this group. This is the baseline group (or put another way, the denominator for all of the comparisons). The conclusions of this study were based on comparing the other two groups to this baseline, and there were too few individuals in this group to be confident that the baseline is accurate.

This does not necessarily invalidate the study, but it does decrease confidence in the size of the reported effect – so forget the reported numbers like 45% increase in mortality and 4-fold increase in cancer deaths. They probably aren’t accurate.

3)     The number of people in this study who died from diabetes was exceedingly small (68 total) and most of them already had diabetes when the study began. The experts concluded that the numbers were simply too low to draw any conclusions about protein intake and diabetes related deaths, and I agree with them.

4)     While the study controlled for fat intake and carbohydrate intake, it did not control for weight. That is a huge omission. Overweight is associated with increased risk of cancer, diabetes and death, and vegetarians tend to weigh less than non-vegetarians.

5)     I would add that there are many other differences between vegetarians and non- vegetarians that could account for most of the differences reported between diets high in animal and vegetable protein. For example:

  • Vegetarians tend to be more health conscious and thus they tend to exercise more, consume more fiber, consume more fruits and vegetables, consume less fried food, and consume less processed and convenience foods – all of which are associated with decreased risk of cancer, diabetes and death.

The Bottom Line:

This is not a particularly strong study. Nor is it particularly novel. In fact, when you strip away the scary headlines and focus on what the data really show, the conclusions aren’t that different from what nutrition experts have been saying for years.

1)     This study suggests that if you are in the 50-65 age range, diets high in animal protein may not be good for you (this study focused on increased risk of cancer death and overall mortality. Other studies have suggested that diets high in animal protein may increase the risk of cardiovascular death).

This is not a new idea. These data are consistent with a number of other studies. However, none of these studies adequately assess whether the increased risk is from the animal protein alone or from other characteristics of populations that consume a lot of animal protein.

2)     This study also suggests that diets high in vegetable protein do not increase either cancer risk or all cause mortality. That’s also not new information. We’ve known for years that people who consume primarily vegetable protein appear to be healthier. Once again, it is not clear whether it is the vegetable protein itself that is beneficial or whether the benefit is due to other characteristics of populations who consume a lot of vegetable protein.

3)     Does that mean that you need to become a vegetarian? It probably reflects my personal bias, but I am reminded of a Woody Allen Quote: “Vegetarians don’t live longer. It just seems that way”. I am also encouraged by studies suggesting that most of the health benefits of vegetarianism can be achieved by diets that consist of around 50% vegetable protein.

I would never discourage anyone from becoming a vegetarian, but if you aren’t ready for that, I would highly recommend that you aim for at least 50% vegetable protein in your diet.

4)     Finally, this study suggests that a high protein diet is beneficial for people over 65. This is also not a completely novel idea. It is consistent with a lot of recent research.

My advice to those of you who, like me, are over 65 is to pay attention to high protein foods and make sure that they are an important part of your diet. I’m not suggesting that you go for the double bacon cheeseburger just because you are over 65. I would still aim for a significant percentage of vegetable protein as a part of a healthy diet at any age.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

Health Tips From The Professor