Indeed, simply eating less than you burn is NOT the "be all, end all of weight loss. This is a misleading assumption and potentially damaging to your health.
A few days ago I was challenged about this. A friend asked "If your view is correct, how come the 'Twinkie Diet' works?" I thought I would share my response with you in some detail.
First, to recap about the 'Twinkie Diet'
Why the 'Twinkie Diet' Doesn't Work Long Term
On this diet, Mark Haub, a Professor of human nutrition eat mostly sugary carbs, especially Twinkies, and reduced his calories from 2,600 kcal per day to less than 1,800 kcal for 10 weeks. He wanted to prove that in weight loss, pure calorie counting is what matters most -- not the nutritional value of the food.
In his view, he proved his point: On his "convenience store diet" he shed 27 pounds in two months. Moreover, other key health indicators improved - his "bad" cholesterol, or LDL, dropped 20%, and his "good" cholesterol, or HDL, increased by 20%. He reduced the level of triglycerides, (a form of fat) by 39%. Haub's body fat also dropped from 33.4 to 24.9 %.
It is true that any severely reduced calorie diet may result in weight loss. But this is likely to be muscle and water loss, especially initially. You don't want to lose any of your muscle because muscle tissue burns calories, but fat does NOT.
I ask you: which is really more important to you? Numbers on the scale or how you look and feel? If you lose 40 lbs, feel weak and are still ashamed to take your shirt off, it’s likely not the outcome you were looking for!
Nor does the 'Twinkie Diet' mean better health long term. As Dr David Katz for example says:
"The mistake is to think this means better health. For one thing, health is a composite of far more than BMI and LDL. For another, its relevant time horizon is far more distant than two months."
Why Eating Less Does Not Guarantee Weight Loss and Robust Health
I elaborated on Dr Katz's comment to my friend by suggesting that eating less does not guarantee weight loss or good health because there are many other factors involved including...
- The thermic effect of the food ingested (TEF): TEF measures how much energy is required to support digestion, absorption and assimilation of nutrients. We "expend energy" by burning calories. Protein carries the highest thermic effect, at around 30%.
- The fibre content: Fibre is a mostly indigestible nutrient. So even though each gram of fibre contains approx four calories, these calories will pass through the intestinal tract largely undigested and unabsorbed.
- The glycemic /insulin indices and glycemic load: The glycemic and insulin indices refer to how quickly a particular carbohydrate source enters the bloodstream as sugar, and how much insulin is needed to rid that sugar from the bloodstream, respectively. The quicker sugar enters the bloodstream, the more insulin is needed to rid that sugar from the bloodstream. When blood contains high levels of insulin, fat burning is brought to an abrupt halt. While the glycemic index tells you only how rapidly a particular carbohydrate turns into sugar, the glycemic load tells you how much of that carbohydrate is in a serving of a particular food. You need to know both to understand a food's effect on blood sugar and can find out more Here (Glycemic Index (GI) and Glycemic Load (GL) Values)
- The macronutrients:Although insulin's primary function is to shuttle glucose (sugar) into skeletal muscle, it also carries many other nutrients to their respective storage sites. Since carbohydrate ingestion stimulates a large insulin response and fat ingestion gives rise to blood lipid levels, the two, when consumed together, promote the greatest fat storage.
- Metabolic slow down:When you restrict calories by eating less or eliminating whole food groups from your diet, you deplete yourself of essential nutrients critical to your health. Your body also goes into a starvation mode to preserve your fat stores. As a result, your metabolism slows to keep you sustained on less food. This slower metabolic rate means that weight loss becomes more and more difficult. Then, when you stop dieting and eat your "old way" again, your body will burn even fewer calories than it did before. Any weight that was lost gets packed back on, plus a few more pounds.
- The size, frequency and timing of ingested meals. Large, infrequent meals tend to promote fat storage of nutrients as the body is unsure as to when the next feeding will take place. Conversely, consuming smaller, frequent meals will result in increased fat loss and utilization of the nutrients. Also, eating a large amount of unrefined carbohydrates before bed spikes insulin, deters overnight fat burning, and increases fat storage during sleep.
- How frequently you exercise and the type of exercise. Many experts now agree that the most effective form of exercise to burn fat, build muscle and reduce weight is a combination of high intensity resistance, interval and cardio exercise.
Clearly, weight loss isn’t just a matter of calories in, calories out. Rather sustained and satisfying weight loss only comes from burning more calories by:
- Consuming fewer calories, and ensuring that those calories have a high thermic effect, and low glycemic index and load.
- Increasing metabolism
- Combining macronutrients effectively
- Consuming small meals often and at inopportune times.
- Practicing regular high intensity resistance, interval and cardio exercise
Perhaps the last words should go to Prof Haub who, despite his temporary success, does not recommend replicating his snack-centric diet. He says:
"I'm not geared to say this is a good thing to do, I'm stuck in the middle. I guess that's the frustrating part. I can't give a concrete answer. There's not enough information to do that."
Hopefully the above gives you more information to make an informed decision!