Why your low calorie diet isn’t working

Why your low calorie diet isn’t working

When faced with the need to shed a few pounds it can be tempting to think that exercise is just for the lycra clad gym bunnies and the smart people can do it by eating a few less calories, while never building up a sweat.

Let’s look behind the calories and numbers to see why this theory isn’t delivering the results you want.
Most people know that to lose the weight we need to consume less calories than we expend or burn during the day. A very common mistake people make when confronted with this situation is to cut their intake of calories right back and the problem with this approach is threefold.

1. Reducing calories to unsustainable levels.

A dramatic reduction in calories will prompt the body to place itself into self-preservation mode. This means it will try and store as many of the calories you consume as it can. Losing weight is actually incredibly stressful on the body and when presented with a rapid reduction in calories the body will resist. When the low calorie diet ends your body will start storing additional fat meaning you end up weighing more than when you started. This is the very nature of the yo-yo diet.

However this is a little simplistic and it’s not until you consider the second reason that restricting too many calories is problematic that the picture becomes a little clearer.

2. Eating too little will lower your metabolism.

Your metabolism is a reflection of how efficient your body is at burning calories, the higher the metabolism the more calories you will be able to burn throughout the day. By restricting the calories you consume you are in fact slowing down your metabolism and its ability to be efficient. The easiest way to understand this is to compare your own metabolism to a roaring fire. We know that to keep a fire burning strong and hot we need to feed it good quality fuel and at the correct intervals. Feed it infrequently and with damp or low quality fuel and it will smoulder and give of little heat.

Consider how your own “fire” burns based on your current eating habits?

Now we know that your calorie intake affects your metabolism we need to consider what happened after we finish a crash diet. We now know that you have made your metabolism less efficient meaning it can no longer burn as many calories as before. This can lead to more energy or calories being stored as fat. If you now try the same crash diet you are likely to find that the same calorie intake is no longer allowing you to lose weight at the rate it did before.

The reaction for many is to cut the calorie intake even further, however as we know this will make the metabolism even less efficient leading many into a vicious cycle.

The final piece of this equation is why your metabolism loses efficiency on a low calorie diet.

3. Loss of muscle mass.

Muscle mass is not referring to bulk such as “body builder” and the principles discussed below apply to every one of all ages and sexes.

When you restrict calories too far it causes the body to lose muscle mass as well as fat. This has a major impact on sustaining your new lower weight for several reasons. Firstly having more lean muscle mass will increase your metabolism significantly. The reason for this is because lean muscle requires more calories to sustain itself. Therefore having more lean muscle will enable you to burn more calories through your day, meaning less spare energy is stored as fat.

Very low calorie diets no longer feed these muscles the calories they need and so they reduce in size. Effectively you have removed a log from the fire of your metabolism.


Looking forward, you have put the weight back on and you want to slim down using your old diet that worked so well before, however you suddenly can’t shift the pounds as quickly or at all.
This is a combination of placing too much stress on the body, suppressing the metabolism by not feeding it enough fuel to keeping burning calories at its previous rate. The reduction in calories in turn leads to the loss of lean muscle and slowing the metabolism even further. For the serial yo-yo dieter this can be a very slippery slope that leads to a slower and slower metabolism and greater weight fluctuations.


A recommended calorie reduction is 200-400Kcal per day will elicit a weight loss of 1-2 per week. Weight loss above 4-5 pounds consistently each week is too high and is unsustainable. The quick fix society is media driven and for you to achieve sustainable health and lifestyle changes you need to make a big shift in your mind set regarding weight loss. If it has taken you two years to gain the extra weight then losing it in eight weeks is never going to last.
Maximize your energy expenditure by increasing your exercise and daily physical activity. A calorie expenditure of 2000Kcal per week has been shown to dramatically increase your chances of achieving sustainable and consistent weight loss. This training should include cardiovascular exercise to promote fat burning and improve cardiovascular health but equally as essential it should include some form of weight training. This weight training can be tailored to all individuals and will help increase the amount of lean muscle and further boost the metabolism, meaning you will burn more fat.

Not sure of your starting calories?

Head over to NHS/BMI and use the free application to calculate your current BMI and calorie requirements.
Many look for a solution in diet or exercise but the reality is they both play an essential role in not only achieving your goal weight but maintaining it for life.


Lifestyle change over diets = Long Term Results

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