This statement is correct: "1 calorie = 1 calorie"
The one is not correct: "1 calorie of egg = 1 calorie of Pepsi"

Saying calories-in-calories-out is like saying, "Winning the Super Bowl is as simple as creating a point deficit in your favor between you and the other team," but not offering any other details about the game of football.

Regarding the liquid diet study, he didn't mention if the subjects experience the same hunger level with the different shakes. Their food was fed to them, so they got the same amount regardless of hunger level. In the real world we have to deal with hunger levels. The article also didn't mention if the nutritional breakdown of the shakes were equal.

Anyone can do simple experiments on themselves involving different macro-ratios. Eat an egg (mostly fat and protein with nutrients) and see how long you can go before you're hungry again. Then drink the equivalent amount of calories of Pepsi as see how it goes.

To answer "is a calorie a calorie" you first have to look at what a calorie is(technically Kilocalorie). It is the amount of energy required to raise a kg of water by 1 deg C. Now with that, our bodies do not extract energy at the same rate from every kcal. for instance, protein will result in a loss of 20-30% waste in the conversion to a useable form of energy. Carbs generally waste about 10% and fat about 2-3%. Now there is still more to the story. A certain amount of fat and protein that you eat is not even used for energy at all, but instead is used for cellular repair, the manufacturing of enzymes, etc. So if you had an extremely heavy workout, those 25g of whey protein are not going to energy (minus the 23-30%) they are going for muscular repair. Where as carbs are just going to energy. So on a hypothetical 2000 kcal diet, if you restrict fat and protein enough, you lose that metabolic benefit. Now on to the issue of hormones. certain macronutrients do affect most, but not all, people differently, and many will find that reducing the production of insulin by reducing carbs will cause hunger to stabalize. Added to that the satiety caused by a greater increase in protein and it becomes even easier to feel full while reducing carbs. Now back to the real question, the answer is yes and no. To lose weight you must burn more calories than you take in, but the types of calories you eat can have a huge affect on how much you burn AND how much you take in. There is the rub.

Have you ever tried to carry a refrigerator?

Is it easier to do so by bear hugging it and lifting or by using a hand truck? In both cases you're lifting the same weight, but in one case its brute force and in another its force intelligently provided.

I'd argue the same is largely true for food. If you consume a caloric deficit, you're going to lose weight (hence the constant reference to thermodynamics). However, this ignores the impact upon your satiety, metabolism, hormones and apetite of a high carb diet. In contrast, if you eat a lower level of carbs, you reach greater satiety and are eating in a manner more consistent with how your body wants to be fed. I'm not a biochemist, but I can tell you its much easier to limit yourself when filling up on eggs than drinking empty calories on Pepsi. I also know that if I eat candy/sugar early in the day, I'm ravenous later on.

Personally, I lost weight via brute force on a "healthy SAD" diet. But, its a thousand times easier to maintain via eggs and meat than bagels and 100 calorie packs.

Hunger control, not calorie control, is the key to losing weight.

Hunger is a form of torture (it's actually used as a torture technique in the real world), that's why we say we're experiencing . When your body makes you hungry, what it's actually doing is torturing you so you'll eat (because).

1) Carbs create the sugar high/crash cycle (http://en.wikipedia.org/wiki/Sugar_crash).

One symptom of a sugar crash is hunger. That's why 3 hours after eating a big pasta meal you not only feel lethargic, you're hungry again.

2) Carbs block the fat/leptin/brain feedback loop.

The more fat you carry, the more leptin in your bloodstream. The less fat you carry, the less leptin in your bloodstream.

When there is a lot of leptin in your bloodstream, your brain (1) increases you metabolism, and (2) decreases your hunger. The result: you lose body fat.

When there is little leptin in your bloodstream, your brain (1) decreases you metabolism, and (2) increases your hunger. The result: you add body fat.

High levels of triglycerides in the blood prevent your brain from detecting leptin in the bloodstream (technically, it prevents leptin from crossing the blood/brain barrier). So, even if you are carrying 100 pounds of extra body fat (and your blood is full of leptin), your brain thinks there isn't any leptin in your blood (and that you aren't carrying enough body fat). So what does your brain do? Reduce your metabolism and increase your hunger, which results in you putting on even more body fat.

High carb diets result in high levels of triglycerides in your blood.

3) High carb diets produces the "insulin lag window."

Insulin in your bloodstream does the following:

• Prevents your fat cells from releasing fat into the bloodstream.
• Causes your fat cells to start absorbing fat from the bloodstream as quickly as possible.
• Causes your body's cells to prefer to burn sugar over any other energy source.
• Causes your liver to step up its efforts to turn sugar into fat (which is immediately absorbed by a fat cell--not burnt by a body cell).

By making fat unavailable to the cells as an energy source, it forces your body's cells to burn sugar which helps clear the bloodstream of excess sugar more quickly. At the end of this process there comes a window where your body has cleared all of the sugar and fat out of your bloodstream, but there is still insulin in your bloodstream preventing your fat cells from releasing fat to be burnt (this, fyi, is the what causes the sugar crash). Despite having eaten a 800 calorie meal just a few hours before, your body doesn't have access to anything it can burn for fuel. So what does your body do? It makes you hungry.

BTW, if you don't eat during this window, your body will start burning muscle cells for energy. This is why people that have lost a lot of weight using calorie restricted diets often end up looking "skinny fat." It's because they haven't just reduced their body fat, they've also lost muscle mass.

4) Calorie restricted diets cause you to go into starvation mode.

When you restrict calories to lose weight, your brain thinks you are starving because of a famine. The result: it lowers your metabolism and increases your hunger.

From a purely theoretical stand point, calories are all that matter. If you don't eat enough calories, you'll lose weight--simple math. But the math of walking from NY to SF also works--just be disciplined and keep walking and you'll get there. But, almost everyone trying this would give up long before they reach SF--it's just too much to ask of the typical human being.

Only focusing on calories requires humans to be "disciplined" and endure hunger pains (a form of torture). Consequently, almost everyone trying this gives up long before they reach their weight goal--it's just too much to ask of the typical human being.

Thinking only in terms of calories causes you to work against your body's natural system for regulating your body fat: the fat/leptin/brain feedback loop. If you take steps to ensure this process works, everything else falls into place and you'll lose body fat--without counting calories and without feeling tortured by hunger pains.

A calorie is a calorie...in a bomb calirometer.

I don't think a calorie is a calorie in a human being, however. We are hormonally complex creatures. Not black boxes run by simple arithmetic.

The nation will start becoming healthier when crappy scientists like Hirsch retire. It can't come soon enough.

There are problems with that study. Dr. Guyenet has some interesting analysis of it.

But Dr. Hirsch is just blathering on in terms of conventional wisdom with no regard for biochemistry. He invokes the first law of thermodynamics, which is what everyone does when they want to say a calorie is a calorie. The first law holds, of course, but there are a lot of subtleties. Such as the thermal effect of food or calories excreted that are not burned or uncoupling proteins that increase heat or people that become more active on a high fat diet.

For the most part, a calories is just a calorie and macronutrients don't matter (for weight loss), but... this guy's just wrong when it comes to there being no better diets than others. Of course there are better diets than others. Comparing isocaloric diets of crap versus highly nutrient dense food, of course there's an advantage for the nutrient dense diet.

Similar to the study where the guy ate nothing but twinkies and ho hos, limited to a certain amount of total calories, and lost weight.

Sure, it worked, but still not quality food.

It's a matter of semantics and it is a distraction. What we are all discussing here are how calories interact with a body. The answer to "whether he's right" is this:

How would your body function if you ate solely the following?

1. A daily diet of 2,500 calories coming from only protein.
2. A daily diet of 2,500 calories coming from only carbohydrate.
3. A daily diet of 2,500 calories coming from only fats.

There's your answer. That useless phrase "A calorie is a calorie" is absolutely untrue, since the body replies to each macronutrient completely differently.

Yes, he is right, but we are not looking for weight loss only, we are after optimum health

First of all, he references work he did on non-obese subjects in the 1950s and 1960s. Then, he didn't read the JAMA study. One of the important findings was that energy use was higher on some of the diets than others. The LFHC actually burned more calories irrespective of consumption. He says in the article that the authors did not provide that information and speculated differences were due to water weight. However, a simple scan of the article (it's available in its entirety to the public) reveals that they measured it two ways and found both methods agreed. The methods used were Respiratory Quotient (RQ) the ratio of CO2/O2 as well as and Food Quotient(FQ) the expected ratio of CO2/O2 given consumption of specific macronutrients. So in other words, respiration in the subjects tracked to higher energy use. This is exactly what you want if you are trying to lose weight.

In my experience, and opinion, macros can affect your BMR and therefore how many calories you need to maintain or lose.

I am happily eating 1600 calories of meat, veg, healthy oils, and some nuts, and losing weight.

When I ate more carbs (or more protein!) I would need to stay more in the range of 1200 calories to lose weight.

His response to the atkins people burning more calories is that lost water "confused the attempts to measure energy output".

His own study that he mentions, he says nothing about protein, only about varying carbohydrate and fat. If you eat low carbohydrate, but high protein, well you are still getting sugar from converting that protein.

I would love a simple study that proved or disproved that high fat, moderate protein, and low carb affects metabolic rate.

Well regardless of whether in most people a calorie is a calorie, low carb, high fat diets do lower insulin resistance, and that may be an obstacle for many people with weight loss.

But then again there may be health issues, in some, with both a low fat diet, and an extremely ketogenic diet.

And then theres genetics. It makes no sense to have a single prescriptive diet recommendation to people with genes which are adapted to very different diets, different metabolisms, and different levels of health and excercise. Theres plenty of science to indicate that food metabolism varies a fair bit with genes, from person to person.

Nutrition really is a vague science too. You cant eat nothing but a single macro, or a single micro for a month and see what happens. In terms of science theres too much to control to ever have much certainty, unless you actually know what happens in vivo, and then that may not apply to everyone.

For me, I just stick to what makes sense, and what I feel good with, with an eye on any science, that makes functional sense.

I think if people are trying to lose weight, they should keep there overall health and wellbeing in mind while they do so, rather than only keep weight loss in mind, which may be dangerous. And they should probably examine any diet guru, paleo or mainstream with a skeptical eye ie think for themselves.

Are we talking about just losing a few pounds, or are we trying to get healthy and get our hormones working again to KEEP the weight off? While you may lose weight for a whole on ANY calorie-deficient diet, you're not really addressing the actual PROBLEM. A calorie IS a calorie, technically, but like someone else said, the way your body uses them is completely different, and the EFFICIENCY with which we use them (as Raise Fitness said) varies drastically based on where that calorie comes from.
You do need to watch caloric intake to lose weight, but you don't need to drop down to a 100 calorie diet to do it. Just be smart with how many carbs you're eating and when you're eating them. Control insulin, regain leptin sensitivity, get your hormones in check, and eat real food. That should be the goal, weight loss will come. Getting healthy is what we should aim for.

Okay, this is another answer I thought about. Its not something ive scientifically researched or understand deeply, but its something that is often mentioned here.

If you are "ketogenically adapted" via a low carb paleo diet, then wouldnt it be then easier to burn fat in a caloric deficit, or via excercise?

I mean if your bodies used to using fat as energy, and you have lots of ketones, wouldnt weight loss be practically easier? At least in people actively losing weight via excercise and caloric deficit...

Talldog is right on. It is an absolute truth that If I create an insulin free environment in my body, I can lose weight AND NOT BE HUNGRY even though I eat 2000 calories a day. 5% carbs 30% protien 65% fat. If I ate the governments recommended high carb lo fat diet and ate 2000 cal per day I would get FATTER. All calories are not created equally: The energy content of food (calories) matters, but it is less important than the metabolic effect of food on our body. Read Peter Attias Blog entry for the simplest explanation ever.

Moron, high fat, low carb diets have been shown over and over again to be superior, he is just telling people what they want to hear. In order to make a million dollars as a dietary expert you have to tell people they can eat pasta and lose weight. While it is possible to do so, it is not sustainable in the long run, but then again...if everyone lost weight diet docs would be out of bussiness