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Eating to Lose Weight

Eating to lose weight. It seems like a bit of an oxymoron doesn’t it? However, there are some strategies that you can employ with your eating habits to make this a reality. Let’s first examine two quick commonly used methods before going to the science.

Negative Calorie Foods

Many of you may have heard about negative calorie foods. If you haven’t, the concept is pretty simple. Eating and digesting a ‘negative calorie food’ will actually take up more energy than what the food provides, and so in effect, you’re actually losing weight while you’re eating. Some commonly quoted examples include celery, broccoli, mandarins and strawberries. Although the idea of negative calorie foods is interesting and appealing, unfortunately, there is very little substance behind it. First off, it is extremely hard to quantify the energy used for digestion for every single food out there. Furthermore, the practice would be rather absurd considering most foods that we eat are eaten with other foods which will change the digestion dynamics.

Thermic Effect of Food

The thermic effect of food (TEF) is the commonly used term for the daily energy used to process and store food and nutrients. Figures differ between sources about how much energy this figure actually is, but is usually around 10-15% of total daily energy use. The reason why foods such as celery, broccoli, mandarins and strawberries are so beneficial in helping to lose weight is due to their low caloric value. And consuming adequate quantities of those acts as a substitute for other foods that you may eat, including high energy foods, which are the ones which will make you put on weight. Many of the ‘negative calorie foods’ are fruits and vegetables, which also contain a generous amount of fibre and may actually aid digestion, making it more efficient. The fibre can also add bulk to your diet which can increase feelings of fullness, possibly reducing your overall intake. So while negative calorie foods may not exist per se, there are several foods out there which have low energy density and high fibre content and can act as a replacement for other foods of higher energy density. Consuming more of these foods can potentially help you lose weight. It is important to remember though that consuming these healthier foods doesn’t give you a free pass to overindulge on a regular basis, otherwise you’ll be stuck in the same spot for awhile.

Weight Loss Nutrients

There are several compounds found in foods that are often believed to help with weight and fat loss. Supplement companies have long taken advantage of such ingredients and have used them in thermogenic supplements said to help boost fat burning through rises in metabolic rate and other mechanisms. Unlike negative calorie foods, many of these weight and fat loss nutrients do possess some ability to help with weight loss and maintenance. One of the most common weight loss nutrients is capsaicin, a compound found in chilli peppers and many other peppers belonging to the capsicum family which give it the characteristic spicy or hot taste. In fact, eating foods containing capsaicin can not only help by increasing your metabolic rate, but can also affect fat burning1,2, appetite levels3,4 and act as an antioxidant due to presence of certain compounds such as carotenoids. In addition, using spices such as peppers can help impart flavour onto foods and as such curb heavy use of salt, fat and sugar. If spicy food isn’t your thing, there are supplements out there containing capsaicin which have negligible taste. It should also be noted that the humble capsicum or bell pepper contains negligible amounts of capsaicin, but are still a low calorie food full of antioxidants.

More Thermogenic Foods

In addition to capsaicin, other common nutrients said to promote weight/fat loss include green tea, caffeine, black pepper, horseradish, bitter orange or the marmalade orange, ginger, turmeric and cocoa just to name a few5,6,7,8,9,10,11,12. Remember that, although there is evidence suggesting benefits of using these individual ingredients for weight and fat loss as well as weight maintenance, many of these ingredients are used in conjunction with various other ingredients for a whole dish. Using chilli peppers, ginger and turmeric in a dish doesn’t equate to eating oversized portions or using generous amounts of oils, cream of butter in your dishes. Similarly, while cocoa has been shown to help with weight, consuming that cocoa as a Mars Bar is not going to offer any benefits. It is important to utilise these ingredients in a manner that promotes what should already be a finely tuned, calorie controlled and nutritious diet.

Macronutrient Distribution

The term macronutrient describes the three major classifications of all the foods that we eat; carbohydrates, proteins and fats. Everything that we eat contains at least one of these macronutrients and in fact most of what we eat contains a mixture of all three. Now we’re told by the media everyday a variety of nutrition tips, some of which can often be confusing and almost contradictory. Eat less carbs, eat less fat, eat more protein, eat more fibre, eat raw foods only, skip out on the sugar. While some of these suggestions have substance, others are more myth than fact. It is also important to realise that lowering the consumption of one macronutrient in your diet will generally mean increasing consumption of another nutrient inadvertently. This is well known in foods displaying the sugar/fat seesaw. That is, foods low in fat will often have more sugar in order to compensate for the taste differences. Alternatively, foods low in sugar will often have a higher fat content. But it’s not all bad; did you know that changing the macronutrient distribution of your meals may help promote fat burning?

The Science – More Reasons to Eat Protein

While research is still continuing, there has been some positive results from a few studies regarding this area:

  • Mikkelsen et al (2000)13 compared higher protein meals compared with  higher carbohydrate meals as well as meat with vegetable protein on 24 hour energy expenditure. They found that a meal with meat protein resulted in higher energy expenditure than vegetable protein and both higher protein meals resulted in greater energy expenditure than a higher carbohydrate meal.
  • Johnston et al (2002)14 compared high protein, low fat diets with high carbohydrate, low fat diets and their effect on weight loss. The researchers found that high protein meals resulted in a dramatic increase in diet induced thermogenesis, which is helpful for weight loss. A further study by Johnston et al (2002)15 was able to show that indeed, high protein, low fat diets over 6 weeks can lead to successful weight and fat loss (6% and 9-11% respectively), greater satiety and satisfaction and better blood markers of cholesterol and insulin.
  • Soenen et al (2010)16 conducted an experiment in which they replaced 2000 kJ or approximately 500 calories per day of food intake with two different supplements. One supplement was predominantly protein, while the other provided equal amounts of carbohydrates and fat. The researchers found that fat oxidation or fat burning was increased in those consuming the protein supplement, pointing to the potential of increasing protein intakes on reducing body fat.

The Science – Burn More Fat During Training

Other studies have looked at macronutrient redistribution and its ability to affect fuel consumption during exercise. Recently Gregory et al (2011)17 found normal metabolism shifted towards greater fat burning straight after a high fat meal compared to a high carbohydrate meal, even though the meals were similar in calories. Furthermore, Gregory et al also found that this shift towards fat burning continued with 30 minutes of exercise. In fact, those who consumed a higher fat meal burned off more energy than those who had a higher carbohydrate meal. This concept of macronutrient redistribution and it affects on fat oxidation during exercise and everyday living has been known for the last 2 decades or so as ‘fat adaptation’ or ‘fat loading’. That is, consuming higher fat meals has the potential to shift your metabolism more towards using more fat as fuel during exercise and even during everyday living. Goedecke et al (1999)18 was able to show that this phenomenon occurred with as little as 5 days of higher fat intake. Furthermore, one can keep this raised level of fat burning even with a day of rest and then a further day of carbohydrate loading. This fact presented an amazing opportunity for many endurance styled athletes to benefit from not only an increased level of fat oxidation, but also a preservation of muscle glycogen to be used during higher intensity activities. Unfortunately, a study by Havemann et al (2006)19 revealed that high fat diets can actually reduce high intensity exercise performance, which may be a result of several proposed mechanisms including a reduction in carbohydrate metabolism20 ability to increase blood levels of noradrenaline which cause rises in heart rate. This may in turn cause an increase in the perceived exertion rating of the exercises.21 In essence however, by eating a higher fat diet, you can increase your body’s ability to burn more fat during rest and during exercise. Bodybuilder’s have been using this phenomenon to create the commonly known ketogenic diet, which promotes high fat, adequate protein and low carbohydrates.

Will Eating More Fat Make Me Fatter?

In theory yes, but it’s also important to realise that the above experiments suggest a macronutrient ‘RE’-distribution. That is, they are swapping carbohydrates for fat, but also keeping the total energy of the meals the same. As such, weight gain is unlikely to occur unless energy expenditure goes down. Many people also worry about whether or not high fat diets, even if isocaloric can cause heart problems. Increased fat intake definitely has the ability to increase fat levels in the body and lead to fat accumulation, even if on a isocaloric diet. Henriksen et al (2008)22 examined high fat isocaloric diets on lean female rats and found that with a higher fat intake, increases in visceral fat (fat around your organs; ie. the more dangerous kind) can occur as well as developments in insulin resistance and impairments with skeletal muscle insulin signalling, which can affect high level sports performance. Similarly, Axen and Axen (2006)23 found that a low carbohydrate, high fat diet led to increases in visceral fat in rats of both sexes, while Estrany et al (2011)24 found that high fat diets only really affected male rats. Estrany et al also found that if 30% of your calories came from fat, increases in adiposity or fat storage occurred. Regardless, it seems that increasing fat levels has strong potential to increase circulating levels of lipids and free fatty acids to abnormal levels. Dyslipidaemia or abnormal fat values as well as increased visceral fat are both considered risk factors for coronary heart disease.

Eating for Weight Loss

Eating should not be feared when it comes to weight loss. Careful meal planning and a good knowledge of food will help you along the way as will employing some of the tips mentioned above including:

  • Substituting lower calorie foods into your diet.
  • Eating or supplementing with thermogenic nutrients such as chilli peppers (capsaicin), black pepper (piperine), ginger (zingerone), cocoa, tumeric (curcumin), caffeine and green tea (catechins).
  • Redistributing your macronutrients.

With regards to the last point, it is still too early to suggest long term use of a higher fat, low carbohydrate diets to promote fat metabolism, as excess fat intake has been shown to result in increased risk of coronary heart disease. These ketogenic diets can be effective in the short term for promoting fat metabolism. However, because health goals change all the time, setting a long term one size fits all macronutrient distribution of nutrients is unsustainable and unwise. In terms of weight loss, the first and most important goal is to have an overall decrease in energy intake. At the same time, it is also important to ensure an adequate protein intake at 15-25% of your total daily energy intake so that weight loss is not accompanied by muscle loss. Keep fat levels under 30% and saturated fat levels under 10% of your total daily energy intake. Ensure that you consume more unsaturated fats such as vegetable fats (not coconut or palm) as this has been shown to increase thermogenesis.25 While low carbohydrate diets are definitely effective in the short term for weight loss, carbohydrate amounts should not drop below 20% of total daily energy intake for a long period of time as this could not only compromise your ability to obtain valuable micronutrients contained in carbohydrates, but also increase your fat and protein intake excessively enough to lead to adverse effects. Carbohydrate levels should theoretically not go below 45% as per recommendations from the Australian National Health and Medical Research Council26,but short term carbohydrate levels below this figure could be employed as a way to promote weight loss. Regardless, it is important to ensure that you monitor yourself very closely and if any adverse or unwanted effects occur, cease the diet and revert back to a simple calorie restricted diet. Additional assistance can be found with any Accredited Practicing Dietitian.


Fact 1: A newly released energy drink by the name of Sweet16 contains capsaicin and a bevy of other ingredients promoted to help with fat burning and energy levels without the need for caffeine.

Fact 2: A kilogram of celery has the same amount of calories as a small McDonald’s fries.


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Lejeune MP, Kovacs EM, Westerterp-Plantenga MS. ‘Effect of capsaicin on substrate oxidation and weight maintenance after modest body-weight loss in human subjects.’ Br J Nutr. 2003 Sep;90(3):651-59.

Reinbach HC, Smeets A, Martinussen T, Møller P, Westerterp-Plantenga MS. ‘Effects of capsaicin, green tea and CH-19 sweet pepper on appetite and energy intake in humans in negative and positive energy balance.’ Clin Nutr. 2009 Jun;28(3):260-5.

Westerterp-Plantenga MS, Smeets A, Lejeune MP. ‘Sensory and gastrointestinal satiety effects of capsaicin on food intake.’ Int J Obes (Lond). 2005 Jun;29(6):682-8.

Shixian Q, VanCrey B, Shi J, Kakuda Y, Jiang Y. ‘Green tea extract thermogenesis-induced weight loss by epigallocatechin gallate inhibition of catechol-O-methyltransferase.’ J Med Food. 2006 Winter;9(4):451-8.

Dulloo AG, Duret C, Rohrer D, Girardier L, Mensi N, Fathi M, Chantre P, Vandermander J. ‘Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans.’ Am J Clin Nutr. 1999 Dec;70(6):1040-5.

Shah SS, Shah GB, Singh SD, Gohil PV, Chauhan K, Shah KA, Chorawala M. ‘Effect of piperine in the regulation of obesity-induced dyslipidemia in high-fat diet rats.’ Indian J Pharmacol. 2011 May;43(3):296-9.

Okulicz M. ‘Multidirectional time-dependent effect of sinigrin and allyl isothiocyanate on metabolic parameters in rats.’ Plant Foods Hum Nutr. 2010 Sep;65(3):217-24.

Haaz S, Fontaine KR, Cutter G, Limdi N, Perumean-Chaney S, Allison DB. ‘Citrus aurantium and synephrine alkaloids in the treatment of overweight and obesity: an update.’ Obes Rev. 2006 Feb;7(1):79-88.

Pawitra Pulbutr, Klangnapa Thunchomnang, Karakate Lawa, Apiwat Mangkhalathon and Pattarapong Saenubol, 2011. Lipolytic Effects of Zingerone in Adipocytes Isolated from Normal Diet-Fed Rats and High Fat Diet-Fed Rats. International Journal of Pharmacology, 7: 629-634.

Ejaz et al. ‘Curcumin Inhibits Adipogenesis in 3T3-L1 Adipocytes and Angiogenesis and Obesity in C57/BL Mice.’ Journal of Nutrition, 2009; 139 (5): 919.

Gu Y, Hurst WJ, Stuart DA, Lambert JD. ‘Inhibition of key digestive enzymes by cocoa extracts and procyanidins.’ J Agric Food Chem. 2011 May 25;59(10):5305-11.

Mikkelsen PB, Toubro S, Astrup A. ‘Effect of fat-reduced diets on 24-h energy expenditure: comparisons between animal protein, vegetable protein, and carbohydrate.’ Am J Clin Nutr. 2000 Nov;72(5):1135-41.

Johnston CS, Day CS, Swan PD. ‘Postprandial thermogenesis is increased 100% on a high-protein, low-fat diet versus a high-carbohydrate, low-fat diet in healthy, young women.’ J Am Coll Nutr. 2002 Feb;21(1):55-61.

Johnston CS, Tjonn SL, Swan PD. ‘High-protein, low-fat diets are effective for weight loss and favorably alter biomarkers in healthy adults.’ J Nutr. 2004 Mar;134(3):586-91.
Soenen S, Plasqui G, Smeets AJ, Westerterp-Plantenga MS. ‘Protein intake induced an increase in exercise stimulated fat oxidation during stable body weight.’ Physiol Behav. 2010 Dec 2;101(5):770-4.

Gregory S et al. ‘Substrate utilization is influenced by acute dietary carbohydrate intake in active, healthy females.’ Journal of Sports Science and Medicine. (2011) 10, 59 – 65.

Goedecke JH, Christie C, Wilson G, Dennis SC, Noakes TD, Hopkins WG, and Lambert EV. ‘Metabolic adaptations to a high-fat diet in endurance cyclists.’ Metabolism.1999;48:1509–1517.

Havemann L, West S, Goedecke JH, McDonald IA, St-Clair Gibson A, Noakes TD, and Lambert EV. ‘Fat adaptation followed by carbohydrate-loading compromises high-intensity sprint performance.’ J Appl Physiol 100: 194–202, 2006.

Stellingwerff T, Spriet LL, Watt MJ, Kimber NE, Hargreaves M, Hawley JA, and Burke LM. ‘Decreased PDH activation and glycogenolysis during exercise following fat adaptation with carbohydrate restoration.’ Am J Physiol Endocrinol Metab. 2006 Feb;290(2):E380-388.
Helge JW, Richter EA, and Kiens B. ‘Interaction of training and diet on metabolism and endurance during exercise in man.’ J Physiol 492: 293–306, 1996.

Henriksen et al. ‘The high-fat-fed lean Zucker rat: a spontaneous isocaloric model of fat-induced insulin resistance associated with muscle GSK-3 overactivity.’ AJP - Regu Physiol June 2008: 294(6): R1813-R1821

Axen KV, Axen K. ‘Very low-carbohydrate versus isocaloric high-carbohydrate diet in dietary obese rats.’ Obesity (Silver Spring). 2006 Aug;14(8):1344-52.

Estrany ME, Proenza AM, Lladó I, Gianotti M. ‘Isocaloric intake of a high-fat diet modifies adiposity and lipid handling in a sex dependent manner in rats.’ Lipids Health Dis. 2011 Apr 12;10:52.

Casas-Agustench P, López-Uriarte P, Bulló M, Ros E, Gómez-Flores A, Salas-Salvadó J. ‘Acute effects of three high-fat meals with different fat saturations on energy expenditure, substrate oxidation and satiety.’ Clin Nutr. 2009 Feb;28(1):39-45.

26 Last Accessed 5th August 2011
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