"...a general public health recommendation for weight reduction through dieting cannot be supported strongly with existing data." -- D.S. Weigle, University of Washington [1 ]
Occasionally, when people hear about focusing on improving food quality instead of worrying about calorie quantity, they react by saying something like: "To lose weight eat less and exercise more... bottom line. I eat whatever I want and stop at 1,400 calories per day... and I've lost 12 pounds. A professor ate nothing but Twinkies and lost a bunch of weight because he cut calories overall... etc."
There's no denying that starvation causes short term weight loss. However, short-term weight loss is not anyone's goal. Long-term fat loss and improved health are most people's goals.
Let's imagine a world where cutting calorie quantity is the key to long-term fat loss. Now let's try an experiment. We'll divide a group of people in half. We'll feed one-half 120 extra calories per day for eight years. What would happen? If weight was ruled by calorie quantity, the math is pretty easy. Multiply 120 extra calories per day times 365 days in a year, times eight years, and the total equals 350,400 extra calories. Take that sum and divide it by the 3,500 calories in a pound of body fat, and we can predict that these people will gain 100 pounds. The equation is easy, but unfortunately, it's incorrect.
Let's look at a real-life study: the $700 million Women's Health Initiative. This study tracked 48,835 women for eight years. Just like our experiment, the women in one group ate an average of 120 more calories a day than the other group. Remember, that adds up to 350,400 more calories. How many more pounds did the women who ate 350,400 more calories gain?
0.88 pounds. 
That is not a typo. Eating 350,400 more calories caused the women to gain an average of less than a pound. It seems that something is not quite right with counting calories to burn fat in the long term.
Quantity-focused fat loss theories incorrectly assume that taking less calories in, or exercising more calories off, forces us to burn body fat. That has been proven false. It does not force us to burn body fat. It forces us to burn less calories. That is why dieters walk around tired and crabby all day. Their bodies and brains have slowed down. 
"Disproportionately large declines in resting metabolism are seen in food-deprived men." -- R.E. Keesy, University of Wisconsin 
When our body needs calories and none are around, it is forced to make a decision: Go through all the hassle of converting calories from body fat or just slow down on burning calories. Given the choice, slowing down wins. University of Wisconsin researcher R.E. Kessey puts it more academically: "Metabolism [is] sharply reduced when an organism falls into negative energy balance." 
What's worse, if our body still thinks we're starving even after it has slowed down, it burns muscle. Only after it starts burning muscle does it begin to burn fat. A lot less muscle and a little less fat today leads to a lot more fat tomorrow.
Bottom line: If we just eat less of our existing diet we will (in this order): [1-10]
- Slow down our metabolism
- Burn a lot of muscle
- Burn a little fat
1 + 2 + 3 = short-term weight loss and long-term fat gain (via yoyo dieting).
This Thanksgiving, don't starve yourself. Don't feel deprived. Starvation isn't sustainable. Hunger isn't healthy. Instead, eat more -- but higher-quality -- holiday foods. For example, non-starchy vegetables (veggies you could eat raw), nutrient dense proteins (seafood and non-processed meats), whole food fats (nuts and seeds), and low-fructose fruits (berries and citrus).
Have a happy holiday, make your forefathers proud, enjoy food again, and stay slim and healthy long-term by focusing on increasing food quality rather than reducing food quantity.
How to Eat More -- Smarter -- This Thanksgiving
Yours in making "healthy" healthy again,
- Jonathan Bailor
- Weigle DS. Human obesity. Exploding the myths. West J Med. 1990 Oct;153(4):421-8. Review. PubMed PMID: 2244378; PubMed Central PMCID: PMC1002573.
- Howard BV, Manson JE, Stefanick ML, Beresford SA, Frank G, Jones B, Rodabough RJ, Snetselaar L, Thomson C, Tinker L, Vitolins M, Prentice R. Low-fat dietary pattern and weight change over 7 years: The Women's Health Initiative Dietary Modification Trial. JAMA. 2006 Jan 4;295(1):39-49. PubMed PMID: 16391215.
- Keesey RE, Powley TL. The regulation of body weight. Annu Rev Psychol. 1986;37:109-33. PubMed PMID: 3963779.
- Benedict, Francis Gano. Human Vitality and Efficiency under Prolonged Restricted Diet,. Washington: Carnegie Institution of Washington, 1919. Print.
- Flatt JP. Conversion of carbohydrate to fat in adipose tissue: an energy-yielding and, therefore, self-limiting process. J Lipid Res. 1970 Mar;11(2):131-43. PubMed PMID: 4392141.
- Acheson KJ, Schutz Y, Bessard T, Anantharaman K, Flatt JP, Jéquier E. Glycogen storage capacity and de novo lipogenesis during massive carbohydrate overfeeding in man. Am J Clin Nutr. 1988 Aug;48(2):240-7. PubMed PMID: 3165600.
- Keys, Ancel. The biology of human starvation. New York: Oxford U.P, 1950. Print.
- Leibel RL, Hirsch J. Diminished energy requirements in reduced-obese patients. Metabolism. 1984 Feb;33(2):164-70. PubMed PMID: 6694559.
- Rosenbaum M, Hirsch J, Gallagher DA, Leibel RL. Long-term persistence of adaptive thermogenesis in subjects who have maintained a reduced body weight. Am J Clin Nutr. 2008 Oct;88(4):906-12. PubMed PMID: 18842775.
- Jen KL, Lu H, Savona L, Watkins A, Shaw M. Long-term weight cycling reduces body weight and fat free mass, but not fat mass in female Wistar rats. Int J Obes Relat Metab Disord. 1995 Oct;19(10):699-708. PubMed PMID: 8589763.