Baked potatoes are a healthy component of a low-fat, whole food, plant-based diet.

For years, I’ve been citing studies that provide evidence for the contribution of dietary fat in the development of insulin resistance and type 2 diabetes. Here’s another, and it’s one great study. It shows that consumption of a high-fat diet makes you spectacularly sensitive to any amount of carbohydrate you eat. This could be why people say that eating carbs makes you fat … the carbs are being eaten against a backdrop of a high-fat diet. Strip away the fat and the carbs you eat won’t make you fat. They also won’t increase your cholesterol, blood glucose, blood insulin, or make you insulin resistant. So says this study:

A Small Amount of Dietary Carbohydrate Can Promote the HFD-Induced Insulin Resistance To A Maximal Level, PloS One, 23 July 2014

Mice were fed one of 5 diets:

• Control diet: 65.1% carb, 23.1% protein, 11.8% fat
• Various High-Fat Diets (HFDs) with increasing amount of carbs: 0.1%, 5%, 10%, 25.5% carb, 58% fat, (protein was varied to keep calories constant)

After 5 weeks:

• “Mice on all high-fat diet (HFD) groups took less food and fewer calories than the mice on chow diet.”

Yet the high-fat-fed mice gained more weight, more body fat, and had higher levels of blood lipids:

• Animals on HFD gained more weight when the level of dietary carbs was increased.
• Mice on HFD with 5% carbs caused absolutely more body weight gain and the HFD with 10% carbs caused equal amount of body weight gain as the HFD with 25.5% carbs.
• White fat proportion was increased in mice on HFD with little (0.1%) dietary carbs, but the increase was further enhanced by dietary carbs in a dose-dependent manner.
• Serum levels of cholesterol, triglyceride (TG), and free fatty acids (FFA) were increased in all groups of HFD
• Together, these results show that dietary carbs are not essential for the HFD-induced body fat gain but can enhance the HFD-induced body fat gain in a dose-dependent manner, and a very small amount of carbs (10%) in the HFD can cause the maximal level of body weight gain.

The high-fat-fed mice had higher levels of blood glucose, blood insulin, and development of insulin resistance:

• Fasting blood glucose level was increased in mice of all HFD groups including the HFD with little (0.1%) carbs starting from week 1, and the increase was promoted by dietary carbs in a dose-dependent manner.
• Fasting plasma insulin level was also increased in mice of all HFD groups, and the increase reached a maximal level when the carbs in the HFD reached 10%.
• Insulin tolerance was significantly decreased in mice on HFD with little (0.1%) dietary carbs, and addition of carbs to HFD worsened insulin tolerance in a dose-dependent manner.
• Animals on chow diet that is a typical high carb (65.1%) and low fat diet (11.8%) did not have insulin resistance.
• Together, these results show that dietary carbs are not essential for the HFD-induced insulin resistance but can promote the HFD-induced insulin resistance dramatically¹, and 10% calories from dietary carbs can promote insulin resistance to a maximal level in mice on HFD.

The high-fat-fed mice also had more fat accumulation in and around the liver. The high-fat diet also induced oxidative stress, not seen in control mice.

Did you see that? The control mice ate more, both in weight of food and calories. But all their lab values were better … and they weighed less!  This has been demonstrated in human studies, both clinical trials (e.g. Barnard’s 2006 study), and population studies, and recently in the experience of Benji Kurtz, who lost over 100 pounds in a year eating his fill of a low-fat, whole food, plant-based diet.

One reason the control mice didn’t gain weight was, as the authors noted, more thermogenesis or heat generation. Eating a low-fat, high-carb diet leads to more thermogenesis, while eating a high-fat diet leads to less body heat (and so more fat accumulation).

¹ “Results from this study show that mice on HFD containing little carb (0.1%) developed severe insulin resistance (Fig. 2). How did that happen? … Glucose from gluconeogenesis is sufficient to stimulate sufficient secretion of insulin, which is necessary for the fat- or glucose-induced insulin resistance.”

CNN just profiled Benji Kurtz, a man who lost over 100 pounds by eating a low-fat, whole food, plant-based diet:
Light Bulb Goes On: He Lost 100 Pounds With Plant-Based Diet, CNN, 28 July 2014

Dr. McDougall also profiled him, in a letter written by Kurtz himself:
Benji Kurtz: A Relatively ‘Healthy’ Obese Person

On Memorial Day weekend, 2013, Kurtz weighed 258 pounds. His highest weight was 278. Kurtz is 5’5″ tall. He was severely obese. He began by eliminating animal food and lost about 50 pounds. The rest came off after he stopped cooking with oil: “I was still eating oily pastas with fried tofu chunks.” And now, a year later:

“I’m down 110 lbs from when I started last year. From my all-time highest weight of 278, I’m nearly half-gone! My BMI is 24.4, and I weigh 146. My cholesterol is at 167 mg/dL, my HDL is 53 mg/dL , LDL is 99 mg/dL, triglycerides are 71 mg/dL, and glucose is 83. My blood pressure 117/77 mmHg and my resting pulse is 54 bpm.”

Kurtz was eating fruits, vegetables, whole grains, and beans. He ate oatmeal for breakfast. He ate red lentil chili, baked potatoes, split pea soup, steamed vegetables, and pastas for lunch and dinner. He ate fruits, nuts, and seeds in between.

“He discovered that he could eat as much as he wanted of the right foods and not gain weight. His new way of eating felt more like abundance than deprivation.”

His cholesterol dropped from over 200 to 167, his blood pressure dropped, his health insurance rates dropped. His energy levels increased, so did his ability to taste:

“Once you start eating this way, your palate totally changes,” Kurtz said. “You are tasting food the way food was supposed to taste in the first place. Like a film has been lifted off your taste buds.”

And:

“I don’t crave foods I no longer eat. I’m not going to bed hungry. Everything about life is better.”

These last two points about taste and cravings aren’t often addressed. Cravings change. Dr. Doug Lisle explains this in his book The Pleasure Trap. We crave the foods we eat. We stop craving the foods we no longer eat. If we continue to eat animal fat, we will salivate over animal fat. We are, in effect, “trapped” by our perceptions, and by behaviors based on those perceptions. This is the part people don’t appreciate. They think life will be hard without “______” and what’s the point in living without “______.” They don’t take the plunge and discover that “______” was just a perception and that it can, quite literally, disappear.

Some before and after photos of Kurtz:

I feel compelled to republish the following post from 6 years ago because people keep asking me how you can get enough protein by eating potatoes.

Me and my potatoes.

Doug asked:

“I still don’t understand why more care isn’t necessary to avoid deficiencies of the essential amino acids. Is it the case that these amino acids are present in all fruits and vegetables? (I didn’t think this was so, but you mentioned on that other thread that thinking has changed in this regard.) Or is it simply that easy to avoid a deficiency of an essential amino acid by consuming any mixture of fruits and vegetables?”

I would answer “Yes” to Doug’s last question. I thought it summed up the facts well.

Plants are capable of manufacturing all 20 amino acids, which include the essential amino acids (EAAs), although amounts vary. I checked a number of foods (potatoes, broccoli, tomatoes, asparagus, corn, rice, oatmeal, beans, and others) and found all EAAs in each of these foods. Even an apple which is listed as having 0 grams of protein has all the EAAs, albeit in small amounts.

Since I said in an earlier comment, “No mixing of foods is necessary. If all you ate were potatoes, you’d get all your amino acids,” I felt obliged to back it up. Below is my back-up.

• The first column lists all 8 EAAs for adults.
• The second column lists the World Health Organization’s recommended intake per body weight.
• The third column lists the specific RDI for a 120 lb adult.
• The fourth column lists the amount of each AA in a medium potato, with skin.
• The fifth column lists the amount of each AA in 5 medium potatoes.
• The last column lists the % of recommended intake (for a 120 lb adult) for each AA when 5 potatoes are consumed.

Some notes about this chart:
– The WHO’s recommended intakes represent the minimum amount for an individual with the highest need, multiplied by a factor of 2 for safety. So these are high amounts to begin with.
– Methionine + Cysteine = Total Sulfur Amino Acids
– Phenylalanine + Tyrosine = Total Aromatic Amino Acids
– WHO: World Health Organization
– EAA: Essential Amino Acid

For a 120 pound adult, five potatoes (960 calories) supply over 100% of the recommended intake for all essential amino acids. They also supply 25 grams of total protein.

It’s pretty difficult for an adult to eat a whole food, plant-based diet that doesn’t provide all the essential amino acids, as long as caloric needs are met.

Finally – The pool of AAs that our body uses to manufacture its own proteins isn’t limited by what we eat. Normal daily turnover of our cells provides a substantial pool from which to draw amino acids. Bacteria that line our colon also manufacture AAs, including EAAs, that we can utilize.

It is a misconception that plants provide “incomplete protein.”

Related: In Defense Of The Potato

I think potatoes are some of the healthiest foods you can eat. They’re full of potassium (40% more than bananas), vitamin C, and fiber. They’re low in calories and they’re fat-free. They provide resistant starch that feeds intestinal bacteria, supporting a healthy gut microflora, characteristics of which (e.g. production of short chain fatty acids) have been shown to lower blood glucose and body fat. And they taste great!

Here’s Dr. McDougall defending the potato:

And here’s Chris Voight, the man that Dr. McDougall mentioned who ate nothing but potatoes for 60 days, about 20 potatoes a day. He lost 21 pounds. His cholesterol dropped 67 points. He lost body fat. His blood sugar came down. His triglycerides came down. Every lab value measured “either stayed the same or got better.”

Voight says, and I agree, that against a backdrop of a high-fat diet, potatoes, actually most high-carb foods can be a problem. In a whole food, plant-based diet, where less than 15% of calories come from fat, potatoes stand out as an excellent food.

Related: If All You Ate Were Potatoes, You’d Get All Your Protein And Essential Amino Acids