What the health: Is it bad to combine carbs, fat and protein in each meal?

31 Jan 2019

a range of different foodsCombining carbs, fat and protein in each meal is commonly referred to using the term ‘food combining’, with the theory being that if you skip certain foods at various times it will allow for efficient digestion, decrease disease risk and toxin build-up.

The theory is based on proteins (meat, poultry, fish, eggs) requiring an acidic environment for denaturation, whereas starchy carbohydrates (rice, pasta, bread, potato) need an alkaline environment. Other rules include not consuming fat with protein, and only consuming fruits/dairy on an empty stomach. If laws aren’t followed proponents of the diet claim you will suffer digestive issues due to partially undigested food that “rots” or “putrefies” causing bloating, constipation, gas or diarrhoea.

The suggested benefits of ‘food combining’ is that it assists in digestion, weight loss, greater energy, better skin, and enhanced absorption of nutrients.

But does ‘food combining’ really work? At the base level it sounds good, however it is only backed by anecdotal evidence. There isn’t any evidence to show such assertions. To my knowledge, only two studies has examined the benefits of ‘food combining’ vs. a balanced diet using body weight as the outcome measure. When matched for energy intake the ‘food combining’ diet did not bring any additional loss in weight and body fat in both studies (see Golay et al., 2000 and Damayanti et al., 2013).

Another major flaw is the misunderstanding of basic biochemistry and physiology of human digestion. Our digestive systems are complex, they can multitask, and digestion happens in other areas besides the stomach – in fact, most of it takes place in the small intestine. Digestion starts in the mouth, continues in our stomach, into the small intestine, and even partially in our large intestine. Sometimes digestion can even go from our stomach and small intestine, back to our mouth, and back to our stomach – like with the breakdown of nitrate. It’s also a lot more complex than saying protein requires an acidic environment for digestion, and carbohydrates require a more basic and therefore once combined neutralise one another.

The human digestive system handles all food combinations very competently and it’s because our diet has evolved on whole foods. The mix can be found in lean meats that contain protein, but also some fat. Vegetables are typically considered carbohydrate foods, but also contain some protein. In fact, vitamins and minerals can enhance absorption when combined. For instance, consumption of meat, fish and poultry can increase iron absorption from plant foods consumed at the same time.

In conclusion, ‘food combining’ isn’t supported by evidence, however if an individual opts to follow this diet it doesn’t have to be bad news. Choosing a diet that encourages a deeper understanding can force an individual to focus on their eating habits. It creates structure, something to stick to, and if it is completed in a non-restrictive way can encourage them to follow a healthy diet. Ultimately, when it comes to our diet, eating a wide-variety of healthy foods from each of the five food groups (grain (cereal) foods – mostly wholegrain; vegetables and legumes/beans; fruit; reduced fat dairy; lean meats and poultry, fish, eggs, tofu, nuts and seeds) in the recommended amounts promotes good health and a reduced risk of disease (see NHMRC, 2013).

Nick McMahonAUTHOR: Nick McMahon is a PhD candidate in the UQ School of Human Movement and Nutrition Sciences. His research is aimed at understanding how best to use dietary nitrate supplements in a safe and effect manner for the enhancement of exercise performance.