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Can A Healthy Diet Help You Lose Weight?

December 30, 2025 by Dr. Steve Chaney

What’s New About This Study?

Author: Dr. Stephen Chaney

New Year’s resolutions are just around the corner. Some of you will resolve to lose weight, and some of you will resolve to eat healthier. But can you do both?

Any restrictive diet will give you short-term weight loss. And weight loss will give you improvement in blood parameters that might signal a reduced risk of heart disease, stroke, and diabetes.

The operative word here is “might”. Long-term studies are required to determine whether a diet actually reduces the risk of chronic diseases.

So, the important question becomes, “Can weight loss diets be 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.

That’s the dilemma most of you face this January. If most weight loss diets are unhealthy long term, do you have to choose between weight loss and good health when you make your New Year’s resolutions?

Maybe not. What if you started from the opposite perspective? What if you asked, “Can a healthy diet help you lose weight?” The study (S Schutte et al, American Journal of Clinical Nutrition, 115: 1-18, 2022)) I will review this week suggests it can.

How Was This Study Done?

This 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%.
A continuation of their habitual diet.

The study lasted 12 weeks. The participants met with a dietitian on a weekly basis. The dietitian gave them all the foods they needed 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 A Healthy Diet Help You Lose Weight?

This study compared a healthy diet to an unhealthy diet with 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.

To 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 added sugars than the “low-nutrient-quality” diet.

When the investigators measured weight loss 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).

- Waist circumference is a direct measure of abdominal obesity.

When the investigators measured blood pressure, fasting total cholesterol levels, and triglyceride levels at 12 weeks:

Prescription for good health overhead with stethoscope, healthy fresh food and exercise equipment, with copy space.

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.

However, the reduction in total serum cholesterol was 2.5-fold greater in the high-nutrient quality diet group than in the low-nutrient-quality diet group.

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 and other added sugars 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, a healthy diet can help you lose weight. Healthy eating helped them lose more weight and gave them greater improvement in their health.

What’s New About This Study?

Simply 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. It is true for any diet that results in caloric restriction.

However, this study breaks new ground in that it shows a high-nutrient quality diet results in significantly better…

Weight loss and…

Reduction in cardiovascular risk factors….

…compared to a low-nutrient quality diet with the same degree of caloric restriction.

What Does This Study Mean For You?

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.

However, 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 your 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) in place of saturated fats.

- The additional omega-3s came from adding a fish oil capsule providing 700mg of EPA and DHA.

Less added sugar.

All these changes make great sense if you are trying to lose weight.

I would group these changes into 7 recommendations.

1) Follow a whole food diet. Avoid sodas, sweets, and highly processed foods.

2) 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.

3) 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.

4) Eat a diet high in natural fiber. Including fruits, vegetables, whole grains, beans, nuts, seeds, and soy foods in your diet is the best way to achieve this goal.

5) 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.

6) Reduce the amount of added sugar in your diet. This is best achieved by eliminating sodas, sweets, and highly processed foods from the diet.

7) 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 or the time you are allowed to 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.

The Bottom Line

A recent study asked, “Can a healthy diet 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 added sugars than the “low-nutrient-quality” diet.

At the end of 12 weeks:

Participants on the high-nutrient quality diet lost 33% more weight and had better cardiovascular markers than participants on the low-nutrient-quality diet.

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.

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My posts and “Health Tips From the Professor” articles carefully avoid claims about any brand of supplement or manufacturer of supplements. However, I am often asked by representatives of supplement companies if they can share them with their customers.

My answer is, “Yes, as long as you share only the article without any additions or alterations. In particular, you should avoid adding any mention of your company or your company’s products. If you were to do that, you could be making what the FTC and FDA consider a “misleading health claim” that could result in legal action against you and the company you represent.

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

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About The Author

Dr. Chaney has a BS in Chemistry from Duke University and a PhD in Biochemistry from UCLA. He is Professor Emeritus from the University of North Carolina where he taught biochemistry and nutrition to medical and dental students for 40 years.

Dr. Chaney won numerous teaching awards at UNC, including the Academy of Educators “Excellence in Teaching Lifetime Achievement Award”.

Dr Chaney also ran an active cancer research program at UNC and published over 100 scientific articles and reviews in peer-reviewed scientific journals. In addition, he authored two chapters on nutrition in one of the leading biochemistry text books for medical students.

Since retiring from the University of North Carolina, he has been writing a weekly health blog called “Health Tips From the Professor”. He has also written two best-selling books, “Slaying the Food Myths” and “Slaying the Supplement Myths”. And most recently he has created an online lifestyle change course, “Create Your Personal Health Zone”. For more information visit https://chaneyhealth.com.

For the past 45 years Dr. Chaney and his wife Suzanne have been helping people improve their health holistically through a combination of good diet, exercise, weight control and appropriate supplementation.

Can Unhealthy Eating Give You Colon Cancer?

December 6, 2022 by Dr. Steve Chaney

What Are Ultra-Processed Foods, And Why Might They Cause Colon Cancer?

Author: Dr. Stephen Chaney

The new year is almost here. If you are like millions of Americans, you may already be making a list of potential New Year’s resolutions and “checking it twice”. If weight loss and a healthier diet are important to you, you may want to put cutting back on ultra-processed foods at the top of your list.

And that’s not easy to do. We love our junk foods and our convenience foods.

It’s so easy to just stop by the nearest drive-through to pick up a quick meal. And we are hardwired to desire sweet, salty, and fatty foods. That’s why we love the taste of junk foods.

We lead busy lives. It’s easier and quicker to pop prepackaged foods into the microwave or oven than prepare a meal from scratch.

Even when we go on a diet to lose weight or improve our health, we want quick and easy. And “Big Food Inc” is only too happy to grant us our wish. They offer ultra-processed meals for every weight loss plan and diet program.

Many of us are second or third generation junk and convenience food lovers. Junk and convenience foods have become normal. Ultra-processed foods now make up 57% of the daily calories consumed by most Americans.

- For example, my mother believed in a balanced diet as long as the foods came from a can or a box. That was normal for me growing up. If my wife had not been brought up very differently, I would not be nearly as healthy as I am today.

Unfortunately, it is becoming increasingly clear that ultra-processed foods are bad for us. In recent issues of “Health Tips From the Professor” I have shared studies suggesting that ultra-processed foods make us fat, increase our risk of diabetes, and increase our risk of cancer. And if that weren’t bad enough, ultra-processed foods give us gas.

The cancer study referenced above showed that ultra-processed foods increased the risk of overall cancer and breast cancer but did not break it down into other kinds of cancer.

Colon cancer ranks third in overall cancers and second in cancer deaths for both men and women. And foods like processed meats are thought to increase the risk of colon cancer. This inspired the authors of a recent study to ask whether ultra-processed foods increased the risk of colon cancer.

What Are Ultra-processed Foods, And Why Might They Cause Colon Cancer?

Ultra-processed foods:

Usually go through several physical and chemical processes, such as extruding, molding, prefrying, and hydrogenation that can lead to the formation of toxic carcinogens that may increase the risk of colon cancer.

- One example you may have heard about recently would be acrylamide in French fries. Another example would be nitrosamines in processed meats.

Are usually high in added sugar, fat, and refined starch which contribute to increased weight gain and obesity, an established risk factor for colon cancer.

Are usually low in phytonutrients, fiber, calcium, and vitamin D, which are known to reduce the risk of colon cancer

Typically contain ingredients of little or no nutritive value, such as refined sugar, hydrogenated oils, emulsifiers, artificial sweeteners, thickening agents, and artificial colors. Some of these ingredients, such as emulsifiers and artificial sweeteners, have been suggested to cause inflammation in the intestine, which is known to increase the risk of colon cancer.

Have long shelf-lives because of added preservatives. This allows migration of carcinogens such as bisphenol A from the packaging materials into the food.

Examples of ultra-processed foods include:

Sodas
Chips
Candy and packages of cookies or crackers
Most breakfast cereals
Boxed cake, cookie, and pancake mix
Chicken nuggets and fish sticks
Fast food burgers
Hot dogs and other processed meat
Infant formula
Instant noodles
Most store-bought ice cream
Flavored yogurt

How Was This Study Done?

This study used data collected from:

The Nurses’ Health Study (NHS) which enrolled 121,700 female nurses aged 30-55 in 1976 and followed them for 28 years.

The Nurses’ Health Study II (NHS II) which enrolled 116,429 female nurses aged 25-42 in 1989 and followed them for 24 years.

The Health Professions’ Follow-up Study (HPFS) which enrolled 51,529 male health professionals aged 40-75 in 1986 and followed them for 28 years.

After excluding participants who had incomplete data or a previous cancer diagnosis, the investigators running the study ended up with 67,425 women from NHS, 92,482 women from NHS II, and 46,341 men from HPFS for analysis.

Ultra-processed food consumption was scored as follows:

The dietary intake of each participant in the studies was assessed with a food frequency questionnaire every four years.

Each questionnaire was scored for the percentage of ultra-processed foods.

Then each participant in the study was ranked in terms of the percent ultra-processed foods in their diet averaged over the entire time they were enrolled in the study.

The participants were then divided into 5 groups based on the number of servings of ultra-processed foods/day they consumed, ranging from a high of 9 servings/day to a low of 3 servings/day.

Every two years the participants were asked to report any cancer diagnosis in the previous two years. Study physicians reviewed the medical records and pathology reports to confirm a diagnosis of colon cancer. If the patient had died, death certificates and medical records were used to confirm a diagnosis of colon cancer.

The investigators then compared the incidence of colon cancer in the group consuming the most ultra-processed foods to the group consuming the least ultra-processed foods.

These comparisons were adjusted for compounding factors like race, family history of cancer, history of endoscopy, physical activity, smoking status, alcohol use, aspirin use, menopausal status, and post-menopausal hormone use.

The comparisons were also adjusted for obesity and a healthy diet score called AHEI. I will explain the significance of these adjustments below.

Finally, the investigators looked at how various categories of ultra-processed food influenced the results.

Can Unhealthy Eating Give You Colon Cancer?

Here is what the study found:

Men in the highest fifth of ultra-processed food consumption had a 29% higher risk of developing colon cancer than those in the lowest fifth.

No association between ultra-processed food consumption and risk of developing colon cancer was seen for women.

When they looked at subgroups of ultra-processed foods again comparing the top fifth in consumption with the lowest fifth:

Consumption of ultra-processed ready to eat products containing meat, poultry, or seafood increased the risk of colon cancer by 44% in men and 14% in women.

Consumption of sugar-sweetened beverages increased the risk of colon cancer by 21% in men but did not significantly affect risk of colon cancer in women.

Consumption of ultra-processed ready to eat mixed dishes increased the risk of colon cancer by 17% in women but did not significantly affect risk of colon cancer in men.

Consumption of ultra-processed dairy products decreased the risk of colon cancer by 17% in women but did not significantly affect risk of colon cancer in men.

The reason for the differing effect of poor diet on the risk of colon cancer in men and women is not clear, but it has been observed in previous studies.

The investigators concluded, “…high consumption of total ultra-processed foods in men and certain subgroups of ultra-processed foods in men and women was associated with an increased risk of colorectal cancer. Further studies are needed to better understand the potential attributes of ultra-processed foods that contribute to colorectal carcinogenesis.”

What Does This Study Mean For You?

There are several take-home lessons from this study:

1: The 29% increase in colon cancer risk reported for men probably underestimates the true risk. I say that because:

Ultra-processed food consumption increases the likelihood that you will gain weight, and obesity is a known risk factor for colon cancer. However, the 29% number was obtained after adjusting the data for obesity. Without that adjustment the increased risk would have been greater

Ultra-processed foods are low in the protective phytonutrients and fiber provided by fruits, vegetables, and whole grains. However, the 29% number was obtained after adjusting the data for a healthy eating index (which includes the amounts of fruits, vegetables, and whole grains in the diet). Without that adjustment the increased risk would have been greater.

2: While we don’t know the mechanism(s) for the increased risk of colon cancer reported in this study, we can make some informed guesses. I say that because:

Once you have removed obesity and fruits, vegetables, and whole grains from consideration, you are left with:

- The effect of ultra-processed foods on your gut bacteria.

- The additives, preservatives, and other potentially carcinogenic chemicals in ultra-processed foods.

3: Finally, don’t think you are off the hook if you are a woman.

As I mentioned in the introduction, ultra-processed foods also increase your risk of obesity, diabetes, and breast cancer.

And that brings us back to what I said at the beginning of this article, “If you are like millions of Americans, you may already be making a list of New Year’s resolutions and “checking it twice”. If weight loss and a healthier diet are important to you, you may want to put cutting back on ultra-processed foods at the top of your list.”

The Bottom Line

A recent study showed that ultra-processed food consumption increased the risk of colon cancer in men, but not in women. The reason for the differing effect of ultra-processed foods on the risk of colon cancer in men and women is not clear, but it has been observed in previous studies on the effect of poor diet on colon cancer risk.

However, don’t think you are off the hook if you are a woman. Previous studies have shown that ultra-processed food consumption increased the risk of obesity, diabetes, and total cancers in both men and women and the risk of breast cancer in women.

That brings me to my recommendation. “If you are like millions of Americans, you may already be making a list of potential New Year’s resolutions and “checking it twice”. If weight loss and a healthier diet are important to you, you may want to put cutting back on ultra-processed foods at the top of your list.”

For more details on this study and what it means for you, 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.