Fat is one of the side effects of capitalism and freedom. Humans evolved under conditions where the search for food was constant. Accordingly, we were programmed to be always hungry. Now that food is available in many parts of the world in almost limitless quantities and at low cost, many of us are too heavy. So many people want to lose weight for either cosmetic, health reasons, or both. The effectiveness of the many diets popularly used is rarely, if ever subjected to rigorous scientific scrutiny. Here are 11 (there are more):
- The Paleo Diet
- The Vegan Diet
- Low Carb Diet
- The Dukan Diet
- The Ultra Low Fat Diet
- The Keto Diet
- The Atkins Diet
- HCG (human chorionic gonadotropin)
- The Zone Diet
- Intermittent Fasting
- The Duke Rice Diet
Why so many? The most likely answer is that they don’t work very well. If one were clearly superior to the others it would be blindingly apparent and every one desirous of weight loss would use it. First a definition. The commonly used, though crude, Body Mass Index (BMI) has a range said to define normal or ideal body weight. A BMI of 18-25 is the most often level used to denote this optimal level of weight. I think that’s too low and that 25-30 is a better value even though many define this range as overweight.
Then there’s the 1st Law of Thermodynamics that cannot be evaded. It’s the one that demands the conservation of energy and mass. Einstein added the interchangeability of the two. One gram of fat burns to 9 calories; conversely, 9 calories is turned to one gram of fat. Thus, to lose one kilogram (1000 grams) of body weight 9,000 calories must burned in excess of intake. One kg equals 2.2 pounds. To lose a pound you must burn a little more than 4500 calories in excess of caloric intake. (In nutrition lingo a kilocalorie is called a calorie.)
Unless you conjure some metabolic magic, a calorie is a calorie irrespective of its food source. If you want to lose weight you must consume less calories than your body uses to keep everything running. What’s the scientific evidence regarding an optimal Diet? Improving the Quality of Dietary Research recently published online by the JAMA discusses the poor state of nutritional research into diets intended to combat obesity.
The authors mention that there currently no evidence for the superiority of one diet over another when the goal is weight loss. There might be better diets out there, but data demonstrating such is lacking. They recommend 10 steps designed to improve the quality of dietary research:
Recognize that the design features of phase 3 drug studies are not always feasible or appropriate in nutrition research, and clarify the minimum standards necessary for diet studies to be considered successful.
Distinguish among study design categories, including mechanistic, pilot (exploratory), efficacy (explanatory), effectiveness (pragmatic), and translational (with implications for public health and policy). Each of these study types is important for generating knowledge about diet and chronic disease, and some overlap may invariably exist; however, the findings from small-scale, short-term, or low-intensity trials should not be conflated with definitive hypothesis testing.
Acknowledge that changes to, or discrepancies in, clinical registries of diet trials are commonplace, and update final analysis plans before unmasking random study group assignments and initiating data analysis.
Define diets more precisely when feasible (eg, with quantitative nutrient targets and other parameters, rather than qualitative descriptors such as Mediterranean) to allow for rigorous and reproducible comparisons.
Improve the methods for addressing common design challenges, such as how to promote adherence to dietary prescriptions (ie, with feeding studies and more intensive behavioral and environmental intervention), and reduce dropout or loss to follow-up.
Develop sensitive and specific biomeasures of adherence (eg, metabolomics), and use available methods when feasible (eg, doubly labeled water method for total energy expenditure).
Create and adequately fund local (or regional) cores to enhance research infrastructure.
Standardize practices to mitigate the risk of bias related to conflicts of interest in nutrition research, including independent oversight of data management and analysis, as has been done for drug trials.
Make databases publicly available at time of study publication to facilitate reanalyses and scholarly dialogue.
Establish best practices for media relations to help reduce hyperbole surrounding publication of small, preliminary, or inconclusive research with limited generalizability.
But no amount of solid nutritional research will remove the need to combine a low calorie diet and exercise when one wishes to lose weight, especially the former. Alas, life is bedeviled by no pain, no gain. You want a diet guaranteed to lose weight and which allows you to eat anything you want? Here it is. Limit caloric intake to no more than 1000. Walk 10,000 steps a day. Do it and you’ll reach whatever weight you desire faster than a gerbil on a wheel.