Updated 02 April 2014

Is alcohol sabotaging your diet?

If you're trying to lose weight, it's best to avoid alcohol altogether, says DietDoc. However, if you still want to enjoy the occasional drink, follow these diet-friendly tips.


If you're trying to lose weight, it's best to avoid alcohol altogether, says DietDoc. However, if you still want to enjoy the occasional drink, follow these diet-friendly tips.

Lately my readers have been flooding me with questions about the energy content of alcoholic drinks. Most people ask; “Which alcoholic drink is better when I am on a slimming diet, whisky and Coke, or a glass of dry white wine?” The basic answer, which I am sure most of you realise deep down, is to avoid all alcohol while you are trying to lose weight. In addition, people tend to forget that there are many non-alcoholic beverages that can also pile on the kilograms. So let’s have another look at alcohol and other drinks, and your attempts to shed weight.

Energy content of alcoholic beverages

Always keep in mind that alcohol will provide 29 kJ per gram or ml, which makes it the second highest contributor to your daily energy intake, after fat which contains a whopping 37 kJ per gram. In comparison, protein (17 kJ/g) and those maligned carbohydrates (16 kJ/g), are quite innocuous.

Four things

The following 4 things will determine how much energy you put into your body when you drink alcohol:

  • The basic alcohol content of the drink. The higher the alcohol concentration, the higher the kJ contribution. For example: on average most types of wine have an alcohol content of 9.4% w/w and provide 300 kJ per 100 g, while spirits such as whisky, brandy, cane, vodka and rum contain 13% alcohol w/w and provide 1044 kJ/100g (3 times more energy than wine per 100 ml)
  • The volume of the drink you consume per serving. In general a glass of wine is about 120 ml which contains 360 kJ, while a metric tot of spirits is only 25 ml which provides 261 kJ. So if you have a whisky with water and ice, you will actually be ingesting nearly 100 kJ less compared to that glass of wine! It is also logical, that the more tots or glasses of alcohol you drink per day, the higher your energy intake will be.
  • What you add to your alcohol. If you add water, ice, soda water, bottled water or artificially sweetened cold drinks to your tot of spirits, the energy content won’t increase, but as soon as you add a mixer that is sweetened with sugar, you will automatically increase its energy content. For example, adding 200 ml of standard carbonated cold drink (350 kJ) to your tot of spirits will push the energy content up to 611 kJ - nearly double the energy contained by the glass of wine.
  • Other components of alcoholic drinks that increase the energy content. Sugar is usually the main culprit when it comes to increasing the kJ-content of your tipple. All the very sweet concentrated drinks, such as muscadel, port, and sherry, contain approximately 580 kJ per 100 ml, and liqueurs top the bill with 1440 kJ/100 ml. On the other hand drier, less sugary concentrated drinks like dry or medium sherry and Vermouth contain less energy (450 kJ/100 ml). Remember just 2 little 50 ml glasses of sherry or liqueur already add up to 100 ml and will add nearly 1500 kJ to your diet.

Drinking recommendations

Based on the above, it is logical that the following rules will help you not to overload with kJ when you do have a drink of alcohol:

  • Select beverages with a low alcohol content
  • Drink small quantities
  • Don’t mix your alcohol with energy-laden cold drinks
  • Avoid sugary, highly concentrated alcoholic drinks like port, muscadel, sweet sherry and liqueurs
  • Don’t drink every day - this will prevent diet sabotage and alcohol addiction.
  • Dilute your alcoholic drinks with zero-energy mixers such as water, ice, soda water or artificially sweetened cold drinks.

What about ‘Light’ beers?

It is highly fashionable nowadays to drink so-called ‘light’ or energy-reduced beers. Such beers do have a moderately reduced energy content, but the energy saving is not massive. Compared to standard Castle Lager which has an energy content of 168 kJ/100 ml, Castle Light contains 129 kJ/100 ml - thus a saving of about 40 kJ per 100 ml or 136 kJ per 340 ml can.

The problem that arises when you drink ‘Light’ beers, is that you may subconsciously be tempted to drink larger quantities at a sitting, than you normally would. Lulled by a false sense of security that you are drinking an energy-reduced drink, you may indulge in 1 or 2 extra cans and end up consuming more energy than when you drink fewer cans of a standard beer. Oh what webs we weave, when we set out to deceive (ourselves)!

Other drinking pitfalls

While we are on the subject of beverages and dieting, it is also important to keep in mind that fruit juices contain energy too. Just because fruit juices are healthy, does not mean that you can have unlimited quantities when trying to lose weight or at other times too.

“I never drink sweetened soft drinks, but stick to healthy fruit juice instead.” is a popular refrain. This is another example of self-deception. Popular fruit juices such as apple or grape juice have an average energy content of about 220 kJ per 100 ml (sweeter juices like grape juice will have a slightly higher energy content, while unsweetened grapefruit juice will contain fewer kJ). If you drink a standard 300 ml glass of fruit juice, you will therefore, ingest 660 kJ of energy, which represents 10,5% of your daily energy intake if you are female or 7.9% if you are male and trying to lose weight or not gain any either.

The problem of fructose

Another problem associated with drinking fruit juice in large quantities is that these juices contain large amounts of fructose (fruit sugar). Some researchers believe that the astronomical increase in fructose intake caused by the change in drinking habits of our modern society, may be responsible for the obesity epidemic and all its attendant ills (insulin resistance and type 2 diabetes; metabolic syndrome; raised blood fat levels, particularly increased triglycerides; gout, because fructose is the only sugar that increase blood uric acid levels; kidney disease; fatty liver, etc) (Van Heerden, 2011).

Current prudent recommendations are that we should be watching our intake of liquid fructose and not indulge in endless glasses of fruit juice all day long. The same applies to our children. Instead of giving your children litres of fruit juice, encourage them to drink clean water or low-fat milk instead. 

Moderation is probably the best guideline. If you can’t avoid alcohol totally when dieting,  drink very circumspectly and try to apply the above mentioned recommendations to avoid sabotaging your diet. Also don’t overdo your fructose intake by having litres of fruit juice every day.

- (Dr IV van Heerden, DietDoc, August 2011)

Any questions? Ask DietDoc


(MRC (2010). Condensed Food Composition Tables for South Africa. Eds. P Wolmarans, N Danster, A Dalton, K Rossouw, H Schonfeldt. Medical Research Council, Tygerberg;  Van Heerden, IV (2011). Metabolic effects of fructose - 2011 Update. Paper presented at the Sugar & Health Symposium, Stellenbosch, March 2011)

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