By Matt O'Neill, MSc(Nut&Diet), APD
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Why do some people fail to lose weight despite cutting calories and boosting exercise? And why do others appear to eat an unlimited quantity of food and not gain weight? New research is now questioning whether calories really matter and pointing towards a different dietary approach to achieve lasting results.
For years the theory has been that if you consume more calories than you expend, you'll gain weight. If you then become obese you may be at a higher risk of metabolic defects like Type II Diabetes.
Now, in 2014, US academic weight loss gurus Professors David Ludwig and Mark Friedman have published a new model of obesity in the Journal of the American Medical Association (JAMA).
Interpreted simply, they say that it's our metabolic chemistry and hormones that get mucked up first and then weight gain follows. Not the other way around.
Sounds complex, so let's break it down.
How we really get fat
The Professors say overeating, particularly sugars and high-glycaemic index (GI) complex carbohydrates, like white bread trigger an increase in blood insulin level.
Insulin's job is to clear the blood of sugars and fats and get these macronutrients into storage in muscles and fat cells.
Insulin generally does this well, leaving lower levels of sugars and fats in the blood stream. According to this new model of obesity, the drop in circulating metabolic fuels in the blood stream provokes hunger and increased food intake.
A vicious cycle emerges, where overeating stimulates insulin production. The ensuing cravings cause more overeating, even more insulin and then eating again.
A drop in circulating metabolic fuels may also act to reduce resting metabolic rate and the energy cost of moving muscles. So, calorie burning drops off too.
And the concern here is that this can be happening when someone is at a normal weight and well before they realise a change in eating behaviour is required to avoid future weight gain and metabolic complications.
The problem with cutting calories
The almost universal approach to counter weight gain has been to create an energy deficit, where you eat fewer calories than you expend. But dieting can exacerbate the biochemical dysfunction by further limiting the shortfall in metabolic fuel availability in the blood stream.
Restrictive diets also set off a series of other compensatory mechanisms that defend an individual's current weight. Energy expenditure decreases due a drop in resting metabolic rate as the body seeks to conserve energy. Hunger levels increase to get you to eat back denied dietary calories.
This explains why so many diets are doomed to fail. Your body fights back to restore the balance. And it looks like hormones are at the centre of how it all works.
A focus on diet composition, not calories
Ludwig and Friedman say a focus on dietary quality over quantity is required to improve metabolic function. Their approach aims to reduce insulin release with a low-glycaemic index or low-carbohydrate diet, whilst not overly restricting calories.
In practice, this means eating a higher-protein, moderate-fat and limited-carbohydrate diet with an emphasis on lower-GI carbohydrates, such as pasta, lentils, basmati rice and some whole grain breads.
Nourishment, not restriction
Other dietary components thought to create the positive biochemical environment necessary for weight loss include; a low refined sugar intake, high polyunsaturated to saturated fat ratio and a high omega-3 and low-trans-fatty acid intake.
A high micronutrient and phytochemical content of the diet may also be essential for optimal metabolic function to promote weight loss. For example, adequate iodine for healthy thyroid function that keeps your resting metabolic rate firing.
The correct balance of intestinal bacteria may also influence how efficiently calories from food are absorbed, highlighting the potential role of probiotics and prebiotics for weight management.
Some slimming diets eliminate dairy and so could be removing the exact foods - probiotic yoghurts - that benefit weight loss.
These new considerations also raise serious questions about how potentially damaging so-called liquid detoxes and cleanses are, when they effectively deprive the body of the wholefood nourishment it needs.
Making every calorie count
Total calories still matter. You can't now eat and drink as much as you like and still lose weight. But it does mean that if you are eating a nutrient-rich diet aligned with good metabolic function and hormonal balance, you may be able to eat more food and total calories and not gain body fat.
Every calorie should offer your body nourishment. For example, eating omega-3-rich fish to reduce metabolic inflammation as well as provide protein. Or eating fibre-rich whole grains as a carbohydrate source that also enhances bacterial balance in the bowel.
What now matters is that every calorie you consume promotes optimum hormonal balance.
Stress and sleep
The Professors also highlight the role of stress and sleep directly or indirectly influence calorie uptake and storage into fat cells.
Research is mounting to show how stress can cause overeating by elevating the hormone cortisol, which stimulates brain neurotransmitters involved in cravings.
Sleep deprivation and broken sleep has now been shown to ramp up the hunger hormone ghrelin and muck up other metabolic processes.
So, effective weight management is not just about food and exercise.
Hormonal balance first
All this considerable research is now pointing towards rebalancing hormones as the prime objective for any dietary intervention for weight loss. The idea is to create the correct biochemistry which in turn switches the body onto fat burning instead of fat storage.
Take home messages
- Total calories still matter, but now so does the quality of calories.
- Restrictive diets, detoxes and cleanses can do more harm than good.
- Focusing on hormonal balance rather than dietary restriction may offer better results.
- Sleep and stress may need to be managed to achieve results.
- Dietary advice for weight loss is becoming more complex, reinforcing the need for fitness professionals to follow general guidelines for healthy eating that promote good hormonal balance.
- Referral to a Doctor or Dietitian for a full assessment of dietary-related hormonal status may provide the best quality of care for clients, in tandem with fitness programs.
Ludwig, D.S. and Friedman, M.I. Increasing adiposity - Consequence or cause of overeating? JAMA. E1-2; May 16, 2014.
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