Which Diet Works Best For Weight Loss?

In the ongoing nutritional war between adherents of low-fat and low-carb diets, the skeptical cardiologist has generally weighed in on the side of lower carbs for weight loss and cardiovascular health.
I’ve questioned the vilification of saturated fat and emphasized the dangers of added sugar  and I consider myself a keto-friendly cardiologist.
Recently I stumbled across a good review on the scientific evidence of various popular diets for weight loss. Obesity and its health consequences are clearly increasing and impacting the cardiovascular health of millions. As such, as a cardiologist it would be great to have a one true diet that is best for weight loss for my patients.
Unfortunately, as I discussed in my analysis of the DIETFITS study there isn’t a one size fits all dietary silver bullet. This recent review does a good job of analyzing the data and has some nice graphics.
Here’s the first graphic which summarizes the food groups allowed for 7 of the most popular diets

Is there any food group we can all agree on?
Yes, the non-starchy vegetables!
Dr. P’s Heart Nuts come in a close second (outlier Ornish recommends “moderation”. Extreme outlier Esselsytn who eschews all oils forbids nuts.)
Interestingly, the only one of these diets that bans red meat, chicken, seafood and eggs is the Ornish diet which is basically a vegetarian diet (see here for the lack of science behind this diet.)
Is there any food group that we all agree should be avoided? If we exclude the outlier Ornish  then there is unanimity that we should be avoiding added sugar and refined grains.
My recommended version of the Mediterranean diet says that high fat dairy is perfectly fine and actually preferred over processed skim or low fat dairy. Yogurt and cheese are encouraged.

Do Macronutrients Matter?

The second graphic nicely summarizes the macronutrient composition of these diets. The Atkins diet and ketogenic diets recommend less than 10% carbs whereas Ornish the outlier recommends less than 10% fat.

My recommended variation on the Mediterranean diet would lower the carb % to around 20% by avoiding starchy vegetables, most added sugar and most refined grains. I try to avoid ultra-processed foods completely. With this diet I am in some degree of ketosis (as measured by the fantastic Keyto device) most of the time although I’m not strictly following keto guidelines.
For example last night I had this delicious steak and smoked portabello quesadilla from Three Kings Pub. The tortilla alone contains about 40 grams of carbs, double the recommended amount for keto diets. I add elements of Three Kings Middle Eastern Sampler (Red pepper hummus, grilled eggplant relish, tzatziki, roasted head of garlic and dolmas. Served with grilled flatbread and an assortment of veggies) to get some of those universally acclaimed nonstarchy vegetables . I don’t utilize the balsamic reduction that is typically drizzled on the quesadilla because it tastes like pure sugar to me (sure enough it contains 11 grams of carbs)and I mostly avoid the grilled flatbread.

 Manipulation Of Diet Timing For Weight Loss

Breakfast is not the most important meal of the day and I only break my overnight fast when I get hungry which is typically around noon.
Variations on this type of intermittent fasting (periodic fasting or 5:2 diet, alternate-day fasting, time-restricted feeding, and religious fasting) have become popular. The review summarizes the science in this area as follows:

“There is growing evidence demonstrating the metabolic health benefits of IF. In rodents, these appear quite profound, whereas in humans they are sparse and need further investigation, especially in long-term studies. It has been suggested that IF does not produce superior weight loss in comparison with continuous calorie restriction plans [130], and there are limited data regarding other clinical outcomes such as diabetes, CVD, and cancer. IF diets seem safe and tolerable for adults…”

In other words, rats live longer with IF but we don’t know if humans do. If you find intermittent fasting helps you consume less calories through out the day and lose weight, go for it. For me fasting from 9 PM to late morning (typically 14-16 hours) give me greater energy and focus throughout the day and makes weight management simpler.

Conclusions: What Is The Best Diet For Weight Loss?

Both low carb and low fat fanatics will be disappointed in the conclusions of the review but I think it is reasonable:

There is no one most effective diet to promote weight loss. In the short term, high-protein, low-carbohydrate diets and intermittent fasting are suggested to promote greater weight loss and could be adopted as a jumpstart. However, owing to adverse effects, caution is required. In the long term, current evidence indicates that different diets promoted similar weight loss and adherence to diets will predict their success. Finally, it is fundamental to adopt a diet that creates a negative energy balance and focuses on good food quality to promote health.

I would
And here is the summary graphic

Dietetically Yours,
N.B. With regard to the starchy vegetables, check out my “Potato Theory of Obesity.”
Source for images: Scientific evidence of diets for weight loss: Different macronutrient composition, intermittent fasting, and popular diets – ScienceDirect
And finally  (from  the  DietDoctor.com website) a graphic that illustrates the amount of healthy (nonstarchy!) vegetables that you would need to consume to reach 20 grams of carbs.


17 thoughts on “Which Diet Works Best For Weight Loss?”

  1. I am a 67 year old, 5′ 10″ tall male who, over the course of approximately two years, lost 80 pounds (from 245 to 165) generally following the Jenny Craig diet. My original goal weight was 174, but at my lowest weight, people commented I should put on a few pounds. I’ve been on statins and BP meds for years. I’ve been able to lower my BP meds, but my cardiologist says I’ll be on statins all my life (I suffered an aortic dissection years ago — treated medically) so I have no problems with the meds. After reaching my goal weight, I transitioned to lower carbs, less processed foods, healthy fats, no fast food, etc. (Alcohol is on and off for me, because its affect on my weight is obvious, but I do enjoy a drink or three.)
    Over the last year, I’ve been gaining and loosing 10 – 25 pounds, but generally not sticking at my goal weight. So when my cardiologist recently ordered blood work which required 12 hours fasting, on a whim, I decided to fast for 3 days. (I had the blood draw after 30+ hours of fasting; all results were good, and have been good since I lost weight.)
    I generally follow IF 14 – 17 hours daily, but I’m interested in longer fasting, like two to four days. While doing my 3 day fast, I read Jason Fung’s book and found it very interesting. I think I recognize quackery, following different sites like Quack Watch and Dr. Harriet Hall’s site. But without asking you to necessarily comment on all of Dr. Fung’s claims for fasting, do you have an opinion about the overall medical safety of longer term fasting (assuming care is taken to stay hydrated, be aware of possible drops in BP, and other common sense precautions)?
    I felt pretty good doing it, and I liked the feeling of taking control of my eating (and drinking) in such a committed manner. But I’ve read things like, “Your body will start consuming lean muscle,” or (literally) “Your body will eat your heart!”
    Such claims seem absurd, but I don’t know . . .

    • Randy,
      Congratulations on losing all that weight! It’s going to greatly benefit your health and longevity. What aspects of the Jenny Craig diet do you think were most beneficial?
      Some thoughts on your case
      1. aortic dissection is not necessarily an indication for statin therapy.
      2. I have no concerns at this point about adverse effects of fasting on the heart. Personally, lately I’ve been fasting 14-18 hours per day and find it gives me more energy and focus. For more prolonged fasting, the evidence for diminishing aging is intriguing but convincing enough at this point for me to recommend widely. Dr. Fung is an enthusiastic proponent of fasting for his diabetic/obese patients and his experience is quite favorable. I definitely don’t consider him a quack.
      Dr P

  2. Over the last couple of years I have enjoyed the Mediterranean diet template, I think it embraces macro groups sensibly and I have had success in losing weight and being satiated. I think your point in choosing a diet that provides negative energy balance and one that can be adhered to long term is really important.
    There is another component of long term weight loss for me that has been far more perplexing than actually losing weight. For most of my life I have had an unhealthy relationship with food, which has resulted in a continuous ebb and flow of my weight. For some, like myself, there is an emotional component to long term weight loss that has to be addressed/resolved in order to achieve long term results. I still use food as a coping mechanism for stress and anxiety, instead of utilizing a healthier outlet. Regardless of what diet you choose, it might be prudent for some to consider what got them to this point in the first place. If you are someone who eats based on your emotional status, one must consider that they have to find another outlet to cope with the rigors of life instead of relying on food.

  3. Dr. Anthony, I think your personal diet is very sensible..so how is it working for you? BMI, pulse BF%, weight, fitness? I know it’s personal but I don’t like taking fitness advice from a smoking cardiologist.
    Dr. Dan

    • BMI 21.9 this morning. Qardiobase calculating my % body fat at 21% for what its worth. Resting pulse upon arising typically 51 with an asterisk.
      Max VO2 calculated from Apple Watch 41 for what its worth.

      • Any preference? – ‘Near’ or ‘Far’ infra red ? Or just plain old-fashioned HEAT ?
        Yes, savagely cutting carbs, moderate protein and ‘ad libitum’ natural & quality fats… strips the pounds off me.
        Exercise such as Resistance and H.I.I.T. benefits me greatly, as does doing it early in the morning in preference to the later evening, where it may disturb my sleep.
        But you should expect “displeasure” from the Manufactured foodstuffs industry.
        And Dieticians…

        • I’ve only superficially looked at the sauna data but my gestalt was to prefer “plain old-fashioned heat.”
          I do think it is problematic to look at weight control strictly from the diet perspective and the vast majority of my patients who successfully keep the pounds off are good at regular exercise.
          A common factor when weight gain has occurred is an inability to do that regular exercise.

  4. In my opinion, weight loss and CV fitness are two different things to consider. You may lose weight eating few carbs but you could end up skinny fat because you can’t walk a mile. As a life-long endurance runner nearing 74 years of age, I have always eaten a good carbohydrate diet supplemented with whatever else I wish to eat. My BMI is close to 25, resting heart rate 38, and I can do the the last stage of the Bruce treadmill maximum exercise tolerance test on the incline treadmill and still take it up to a 26% grade. 4% higher than the Bruce. No one else in the gym can even come remotely close and the cardiologist who writes this blog wouldn’t either. How, then to do this? Just eat fresh food. Eat lots of fruits and vegetables, some lean meat as you chose. I personally, do not like to eat or drink any dairy products because they cause nausea in me personally. Don’t smoke, drink booze, use dope and get plenty of exercise. You will not only loose weight without following a special diet, you will feel better than you have ever felt in your life. Is this difficult to do? Well, considering how great you feel and how sh@@ty you would feel otherwise, I don’t think so. What do you think? Is it worth having low total cholesterol, low LDL, no diabetes, no hypertension and never being sick through your 60’s and 70’s? How about never even having a cold in more than 10 years? Well, I am truly grateful for following my own advice. That is I have never read or followed a diet written or suggested by someone else in my life.

  5. ACP is a smart fellow: he is on the right track. The BEST weight loss diet is the one that works. Generally high protein diets are “more satisfying” resulting in less hunger. Hunger is actually your friend if u can get past it, hunger is the very second u r losing weight. Now the the healthiest diet is the one that fits with our biology: flat grinding teeth, enzyme to digest CHO/plant food in our saliva, can’t digest rotten meat,…. palm sized serving of wild caught game every 10 days. We are essentially vegan by design, a least 90%. Follow that or suffer the consequences. Intermittent fasting is a great idea: eat in only 9 hours (8 is just a little too difficult) from when u arise; go to bed wi an empty stomach. I thimk the ideal weight loss diet is berries in a green smoothie wi Spring Mix + 4 oz almond or rice milk or Pom Wonderful + 1 scoop unflavored hemp protein powder).Cooked veg & veg soups for lunch wi 3 oz lentils. Dinner = more cooked veg/veg soups + 3-4 oz chick peas or other beans. After the 9 hours, tea wi lemon or lime with our without more steamed veggies (no potatoes of any kind at any time). See your MD or dietitian every 2 weeks till weight loss begins and then -> 4, 7, 11, 16 weeks,…. Variations gently introduced.

  6. Balanced, objective, superbly-written analysis and commentary by Dr. Anthony P. Would very much appreciate Dr. P’s thoughts on 22-hour IF (from 9 pm to 7 pm) – One Meal A Day?

  7. I’ve been reading a lot about AI and big data and think the future will bring individualized diet plans based on the person’s genetic data, medical profile, and other relevant factors such as the type of work (sedentary, active, etc.) in which the person engages, types and amounts of exercise per week, environment (in the broad sense – who one lives with can hinder or facilitate a diet) and more. I have a diabetic friend who has lost a lot of weight and reduced her A1c on a doctor supervised vegan diet, a diet I’d consider a form of torture. I’m very sensitive to sodium so need to avoid high sodium dishes. I agree with you that added sugar is a major culprit, and that is what I have the most trouble keeping to a minimum.


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