Carbs, Weight Loss and Metabolism

Personal Healthcare

Type 2 diabetes has tripled over the past 10 years and 61% of Australians are now overweight or obese (ABS statistics) and this at a time when apparently it is well known that the best methods for controlling weight involve lifestyle changes in diet and exercise. Clearly, something is wrong. Thirty years ago, the Lausanne group showed that carbohydrates in food were a minor contributor to fat accumulation in obesity (1-3). This supported the dietary recommendations at the time that most of the diet should be made up of carbohydrates, with fat being limited to 30% and protein to the 10-20% range. The worsening health status, however, indicates that either:

      1. People are not complying with the dietary recommendations, or

      2. These recommendations are not appropriate.

A review has recently been published that re-examines the evidence for low-carbohydrate and Paleolithic diets with reference to the current and proposed dietary guidelines.


 Low-Carbohydrate Diets:

  • A number of recent intervention trials have shown that it is advantageous to consume a low-carbohydrate diet with regards to body weight and metabolic control.
  • Nordmann et al. (4) demonstrated that low-carbohydrate diets were at least as effective as low-fat diets for weight loss.
  • Two studies comparing the Atkins, Ornish, and Zone diets on metabolic risk factors and weight loss over one year concluded that low-carbohydrate diets were favorable for weight loss and improvement of cardiovascular risk factors.
  • The OmniHeart trial compared 3 diets:
  1. The first consisting of 15% protein, 58% carbohydrate, 27% fat
  2. The second where 10% of energy from carbohydrate was replaced with protein and consisted of 25% protein, 48% carbohydrate, and 27% fat
  3. The third where 10% of calories from carbohydrate was replaced with unsaturated fat and consisted of 15% protein, 48% carbohydrate, 37% fat.
  • The results indicated that the diets where 10% of calories from carbohydrate were replaced with either fat or protein resulted in lower systolic and diastolic blood pressures, further improved blood lipid concentrations, and further reductions in cardiovascular risk compared to the first diet.
  • In another study, Reaven found that reducing carbohydrate and replacing it with unsaturated fat resulted in improved cardiovascular disease risk factors.
  • Other short-term studies along with new research reported on the ABC pm program on 17/11/11 has reinforced that a high-protein diet increases a feeling of fullness and leads to reduced spontaneous eating as well as lower body weight, and body fat. These diets have also shown improved insulin sensitivity, glucose control, and decreased leptin concentrations in overweight and obese subjects.

Paleolithic Diet

  • The Paleolithic diet (5) provides a macronutrient distribution in the range of 19-35% protein, 22-40% carbohydrate, and 28-58% fat.
  • Even though this diet was relatively high in fat, it would have included high levels of mono- and polyunsaturated fatty acids and a much lower omega-6/omega-3 ratio than current Western diets do.
  • Recent studies of the Paleolithic diet have shown that it provides the health benefits of reduced blood pressure, decreased insulin after a meal and glucose responses to an oral glucose tolerance test, and improved blood lipid profiles.


These results indicate that diets that involve reducing (NOT eliminating) carbohydrate intake with a corresponding increase in protein or unsaturated fat can result in lower systolic and diastolic blood pressures, improved blood lipid concentrations and reductions in cardiovascular risk.

Bodywise Comment

First, it must be said that these studies are just that studies and anyone, especially if you have a medical condition must seek advice from your doctor or health professional before undertaking a new diet or eating plan. High protein diets can be dangerous for people some people including children, athletes (or very active people) as well as people who have high blood pressure or gout. High protein diets can also cause some severe health complications including constipation, diarrhea, bad breath, headache, kidney problems and colorectal cancer.

The Dietary Guidelines for Australians states that to prevent weight gain: be physically active and eat according to your energy needs. Some people now argue, however, that manipulating the amounts of different types of food in one’s diet can assist reducing the overall calorie intake, reducing body fat and weight whilst also lowering blood pressures, improving blood lipid concentrations, and reducing cardiovascular risk. These studies support this position.

The Great Carb Debate

On the face of it, it would seem that the answer is to reduce carbohydrates and increase proteins and unsaturated fat in our diets. However, as with so many things in life, it isn’t quite that simple.

Do grains make us fat?

Advocates of high protein/carbohydrate diets argue that grains make us fat. This flies in the face of the fact that we have eaten grains for thousands of years and it is only in the last 20-50 years that being overweight and obesity has become an epidemic. In that time, grains have been refined down to make white flour or white rice from which we make bread, cereals, biscuits and cakes. When digested, the individual sugars (principally glucose) from these refined grains are absorbed into the bloodstream very quickly causing a large increase in blood glucose. How quickly glucose enters the bloodstream after eating forms the basis for the glycemic index (GI). Foods that cause a large rise in blood glucose have a high GI and those that cause a low rise have a low GI. From a blood glucose standpoint (high GI), white flour is much worse than sugar. After eating cakes, biscuits and other foods that contain flour and other refined grains, blood glucose levels spike. In response, the pancreas floods the bloodstream with the hormone insulin. Insulin is a storage hormone and stimulates the storage of incoming fat, carbohydrate and protein into muscle, liver and fat cells. The body runs much better when the level of glucose in the bloodstream is kept constant. Protein and unrefined carbohydrates (i.e. low GI foods), reduce the rise in blood glucose following a meal and therefore reduces the subsequent amount of insulin released to deal with the meal. Less insulin means less fluctuation in blood glucose and less likelihood that you will hungry 1-2 hours after eating. Refined grains and processed foods blood glucose to rise too high. Eating food that contains primarily proteins and fats causes blood glucose levels to fall too low. Neither is good.

Refined carbs are the problem

Today, the main problem is that our excessive high carbohydrate / GI diets overload the system so that either not enough insulin is released or the body’s cells have become desensitized to insulin. Both of these problems mean that glucose is not absorbed into the body’s cells, which leads to high levels of blood glucose and diabetes.

Glucose spikes and high levels of insulin after eating high GI foods have been shown to cause damage to blood vessels, inflammation, as well as be a risk for cardiovascular disease. Consequently, if you have any inflammatory condition or cardiovascular disease, it would be a good idea to avoid high GI foods and choose low GI ones instead. Low GI foods include most unrefined grains and fruit. The table lists some common low and high GI carbohydrate foods:

  Traditional low GI foods     Modern high GI foods
Stone Ground Bread White Bread
Sourdough Breads Regular Wholemeal Bread
Heavy Grainy Breads Most White Rice
Porridge, Oats and Some Muesli Most Breakfast Cereals
Legumes (lentils and beans) Most Snack Bars and Biscuits
Most Fruit Potatoes, Chips and French Fries
Rye, Barley, Quinoa Scones, Cakes, Pikelets, Pancakes
Cracked Wheat, Buckwheat Bagels and Crumpets

 Important points in the great carb debate

  • Whole grains, legumes (beans) and pulses (lentils) provide essential nutrients and fiber that our bodies need
  • Whole grains, legumes and pulses and are cheap and convenient making them easy to include in a modern time poor lifestyle
  • Carbohydrates are essential for optimal thinking (e.g. memory and concentration) as well as exercise and bowel health
  • The piles of earth resources could not support the world’s population if our diets became mainly meat based
  • Hunter-gatherer man (paleolithic diet) ate more fruit and vegetables as well as parts of animals that we no longer eat. It is difficult if not impossible to replicate a paleolithic diet
  • The GI is a great instrument in helping us choose better carbohydrates
  • You can choose not to eat or reduce grain foods but you must seriously increase your uptake of other plant foods.

The healthiest diets for optimizing weight control recommend:

  • A modest increase in lean protein and vegetables, with a complementary modest decrease in unrefined carbohydrate and fruits mealtimes, try dividing your plate into 2/3s vegetables, 1/3 protein
  • Getting your protein from lean meats, fish, chicken, eggs, legumes and nuts Best include: game meats (e.g. venison, kangaroo), oily fish (salmon, mackerel), chicken/turkey breast, free range eggs, low-fat milk and pro-biotic yogurt, seafood
  • Getting your carbohydrates mainly from vegetables, with a less amount from unrefined grains and fruit Best vegetables include: kale, asparagus, broccoli, Brussel sprouts, Asian greens, spinach, rocket, endive, cabbage, capsicum, mushrooms, etc. Best grains include: barley, beans, lentils, oats, muesli, quinoa, bulgur wholemeal pasta and bread including grainy sourdough, pumpernickel, stoneground and wholemeal, etc Best fruit include: apricots, pomegranates, berries (raspberry, blueberries, etc.), citric (oranges, etc.), kiwi fruit, papaya
  • Have smaller portions and eat smaller meals (perhaps ½ -2/3s meal size) more frequently (6 times /day)
  • Eat slowly and when relaxed, putting down your knife and fork between mouthfuls
  • Drinking plenty of water (e.g. bodyweight in kgs x 0.033 = amount in liters to be drunk each day  reference Paul Chek)
  • Eat fresh foods as much as possible (aim for 1/3 of your vegetables raw)
  • Where possible, eliminate/limit processed foods especially those with flour (unrefined grains) excessive sugar, especially fructose (aim for less than 10%, i.e. less than 10g per 100g)as well as excessive salt
  • Choose low-fat options when possible (aim for less than 10%, i.e. less than 10g per 100g)
  • Allow yourself occasional treats
  • Listen to your appetite and enjoy your food.

For more information or for an appointment, please call Bodywise Health on 1 300 263 994.

Please note:

  • Rebates are available through your private insurance extras cover
  • For complex or chronic conditions, you may qualify for the EPC (Enhanced Primary Care Program) allowing you to receive 5 allied health services each calendar year with a referral from your GP. For more information, please call Bodywise Health now on 1 300 263 994.

Research Reference:  Nutrition 2010; (26) 141145.

Other References:

  1. Acheson KJ, Flatt JP, Jequier E. Glycogen synthesis versus lipogenesis after a 500-gram carbohydrate meal in man. Metabolism 1982; 31:123440.
  2. Acheson KJ, Schutz Y, Bessard T, Anantharaman K, Flatt JP, Jequier E. Glycogen storage capacity and de novo lipogenesis during massive carbohydrate overfeeding in man. Am J Clin Nutr 1988; 48:2407.
  3. Acheson KJ, Schutz Y, Bessard T, Ravussin E, Jequier E, Flatt JP. Nutritional influences on lipogenesis and thermogenesis after a carbohydrate meal. Am J Physiol Endocrinol Metab 1984; 246: E6270.
  4. Nordmann AJ, Nordmann A, Briel M, Keller U, Yancy WS Jr, Brehm BJ, Bucher HC. Effects of low-carbohydrate vs low-fat diets on weight loss and cardiovascular risk factors: a meta-analysis of randomized controlled trials. Arch Intern Med 2006; 166:28593.
  5. Eaton SB, Eaton SB III. Paleolithic vs. modern diets selected pathophysiological implications. Eur J Nutr 2000
  6. McMillan Price, Joanna & Davie, Judy. Star Foods. ABC Books, 2008.
  7. Check, Paul.  How to Eat, Move and Be Healthy. California: C.H.E.K. Institute, 2006
  8. Tickell, John.  The Great Australian Diet. Melbourne. 2004