By Nantege Regina _B.Sc. Dietetics, MSc. Human Nutrition

Unintentional weight loss during peak sports training months can be prevented. Unintentional weight loss means that the weight loss adds no advantage to your sports performance. This article is for you if you are already at a healthy weight and weight loss would result in a low weight for height making you underweight. If both illustrations of un-intentional weight loss apply to you then take these 3 actions;

Disclaimer: This article is not for individuals who are overweight or obese. It is for highly active normal-weight persons.


Calculate the additional energy expenditure related to exercise. (BMR + Exercise Expenditure Energy) for example; Regan has a BMR of 2,000 to which he adds 2,000 Calories expenditure during a 28km run from Lubowa to Cricket Oval which means that the day's Energy Expenditure is 4,000 Calories. Regan will use this calculation in Action 2 to understand why weight loss happened and in Action 3 to address the problem.

Justification: The average adult uses 2,000 Calories for men and 1,800 Calories for women without factoring in active physical exercise. The physical activity expenditure increases daily energy output and we must eat all the calories to avoid weight loss as explained in part D.

Note: Energy Expenditure varies according to age, weight and height. Please ask a Dietitian.



Why Am I Losing Body Fat But Not Weight?


  1. A Drop in Muscle Mass over weeks of training.

During extreme training, your body has a higher protein need to support muscle tissue repair and building. If you do not eat the needed amount of protein, you will drop muscle mass despite training to build muscle. This is because the training load triggers a need for better muscle but without the raw material (protein) then muscle cannot be built. 

Yes, this affects recovery and reduces performance.

Note: You may have signs of facial muscle wasting that make people say you look a little older. This is also associated with loss of fat in the facial area.

Take Action: Runners need 1.2-1.4g of Protein per kg of body weight. This is higher than the normal adults 0.8g/kg of body weight. The requirement for Ultra-Endurance Athletes is even higher at 1.2-2.0g/kg Example: Regis who runs 21kms occasionally is 60kgs and needs 1.4g per kg she needs 90 grams of protein per day.  Regan is an 80kg male training for the Comrades Race and runs 40-50 km often so needs 160 grams of protein (2*80).

To meet their protein requirements, they eat as follows:


Regis’ 84 Grams Protein Goal

Regan’s 160gram Protein Goal

Post-run snack

2 Beef Samosas or 3 Egg Whites

Or 1 scoop of Protein Powder

3-4 Beef Samosas or 6 Egg Whites

Or 2 Scoops Protein Powder


2 Cups Milk Tea or Plant Dairy (500ml)

4 Cups Milk Tea or Plant Dairy (1 liter)


Bowl full Bean stew or 200g Fish or ¼ Chicken

2 Bowl full Bean stew or 400g Fish or ½ Chicken

Evening Snack

60g Roasted Groundnuts or Almonds

120g Roasted Groundnuts or Almonds


200g Lean Beef / Pork (2 Skewers)

400g Lean Beef / Pork (4 skewers)

 Note: The upper protein limit is used on active days for example; Regis’ lower limit is 1.2 and the upper is 1.4g/ kg. 

Observation: You do not need protein supplements if you can eat all the protein from enjoyable foods. However, if you typically have no time for meals then protein powders come in handy.

B. Glycogen Stores Depletion Post-Exercise if not Replenished that Day

Can You Use Fat As an Energy Source for Running? | Fitpage

Endurance athletes with a higher muscle mass have a fueling advantage as muscle is a carrier for Glycogen which is broken down to glucose for energy during activity. This is a faster source of energy when compared to fat burning. This means that during exercise, runners utilize their glycogen stores and commonly deplete them. Depleting 400g of muscle glycogen means you need to replenish carbohydrates in your post-run diet.

It is a common myth for runners to carbohydrate load before an event however the better practice to carbohydrate load is hours after each training or race. This returns your glycogen stores to their normal threshold, storing up enough for your next activity. 

Furthermore: It is important to note that the higher the muscle mass, the higher the glycogen storage capacity. One must therefore strength train to increase muscle mass otherwise eating too much carbohydrate without storage space results in excess carbohydrate being stored as fat which is still fuel but has a longer breakdown pathway.

Take Action: Aim at loading a minimum of 400g of Carbohydrates within 6 hours after a long run (over 21kms). This will contribute 1,600 Calories to replacing the calories used in exercise.

Sources of 400g Carbohydrate: 

  1. 2.7 liters Sweetened Packaged Juices for example 100ml minute maid has 15g Carbohydrate so 2.7 has 405g Carbohydrate. 
  2. Energy Bars: Snicker bars contain 35g of carbohydrates and 280 Calories partly from fats. 
  3. Fruit is a great choice as it also has minerals, vitamins and fibre eg sweet bananas
  4. Starches from Cassava, Potatoes, porridge
  5. Note: Drink as much carbohydrate if you find hard to eat after a race.



We will use Regan’s example: he uses 4,000 Calories on the day he runs Lubowa to Entebbe; to eat back 4,000 Calories he will have to eat as follows or he lose weight.

Another example will be if Regan decides to train for Comrades and he has days he runs 60kms which uses 4,800 Calories plus the 2,000 Calories associated with his Basal Metabolic Rate making his day’s energy need 6,800 Calories. It is very easy for Regan to lose weight if he does not follow a routine similar to the one below.

Meal/ Snack

Day of 28km Training

(4,000 Calories)

Day of 60km Training

(6,800 Calories)

Pre-Run Nutrition

(1 hour before)

100-200 Calories

300ml Sweetened Fruit Juice 

(remove fibre by sieving)


300ml Maize or Millet or Rice or Oats Porridge (low fibre options)

During Run Fuel

16-240 Calories per hour

(not eaten at once)

40-60g Carbohydrate Gel/ Sweetened Drink/ ¾Energy Bar per hour

*3 (3 Gels or 3 bottles of sweetened drinks or 3 Energy Bars)

40-60g Carbohydrate Gel/ Sweetened Drink/ ¾ Energy Bar per hour

*6 (6 Gels or 6 bottles of sweetened drinks or 5 Energy Bars)

Post-Run Fuel

300-400g Carbohydrate -1,200 to 1,600 Calories

2 liters sweetened fruit juice

Or 2 Energy Bars 

Or 1.5 liters of Fermented Bushera 

Add Protein

2 liters sweetened fruit juice

Or 4 Energy Bars 

Or 3 liters of Fermented Bushera or Porridge

Add Protein

High Protein Breakfast Example

500 Calories

Typical Ugandan Breakfast with extra protein.

Eg: Katogo of Matooke and Chicken with Vegetables

1,000 Calories

Typical Ugandan Breakfast with extra protein

Add: 1-liter sweetened drink/ 2 muffins


Note: items listed are simply examples.

800 Calories

Healthy Plate with a 500ml Sweetened Drink eg; 

Boiled matooke, rice, liver and stir-fried cabbage plus 500ml Mango-Hibiscus Juice

Drink: 500ml sweetened juice

1,200 Calories

High oil-high carb-high protein meal eg;

Rice, Liver, Steamed Doddo, Fried Chicken and 1 whole avocado

Drink: 1 litre sweetened juice

Evening Snack Example

150 Calories

60g Groundnuts

1 apple/ Slice of watermelon

300 Calories

120g Groundnuts

Bowl of fruits

Dinner Example

500 Calories

Normal Healthy Plate Meal


1,200 Calorie meal

Deep oil fried meal or high fat meal eg chips or deep-fried chicken

Note: If you have no appetite eat a high-energy snack or supplement for example using 2 Energy Bars each with 500 Calories to make 1,000 Calories. (Snicker bars as an example of high-energy bars have 14g fat to complement the carbohydrate which may not be tolerated by some runners as a during run meal so you may opt for lower fat options during fast runs)

This is an example and getting/ making a personalized plan allows you to work with your preferences.

Altering energy intake with the amount of energy used per day is advised to avoid overeating on low-activity days.


D. Could it be Post-Exercise Dehydration? A Drop in Water Mass

Using Regan as an example; Regan had a slightly low appetite for food after the run, he focused on drinking his rehydration fluids and salts which ensured he retained his weight lost due to sweating. Typically, he weighs a kg less after a run if no re-hydration is done. By rehydrating with a total of 1-liter of fluids (during and post-run), he was able to regain his before-run body weight. This is a clear indication of proper re-hydration when pre and post-run weight and compared.

The above scenario; removes the factor of dehydration as a cause of weight loss as this is addressable by rehydration within hours after a run. Note: Over-rehydration and hydration with no Sodium and Potassium replacement is discouraged.

Take Action: Understand your sweat output and re-hydrate adequately after each run. Easy approach: your sweat output per hour is the difference between pre-run and post-1-hour run without any hydration or urination. This varies with individuals, seasons and pace. Averagely 1kg is lost which is 1 liter of fluids per hour, you may only handle 300-500ml per hour during the run which means you drink the 500-700ml post-run.



You cannot perfect your exercise nutrition in one day. Take on one habit at a time for example;

Week 1

Perfect your protein intake using the protein intake table. Ensure you stock up all your protein sources at the start of the week.

Week 2

Perfect your post-run fueling (400g Carbohydrate) using the Glycogen stores section. Learn to stock post-run fuel into your changing clothes pack.

Week 3

Master Run Hydration and During Run Fueling (40-60g carbs per hour)

Week 4

Perfect your calorie intake using the example above.

Month 2 (Week 5-8)

Master your Full Exercise Nutrition Routine


1. Skip the counting of macros and calories. You can take pictures of everything you eat and upload them to the Lya Dietitian App for analysis. Download the Lya Dietitian App and Call 0784200201 to take advantage of the free meal analysis offer. 

2. The biggest struggle is increasing calories so eat/ drink higher-calorie foods for example during your post-run meal; it is wrong to fill up on water when you can take water plus calories in a sweetened drink or protein-rich milk tea or a porridge. You may also benefit from adding oils to your juice blends for extra calories. 

3. When choosing vegetables; always include avocados as they are high in oil and calories.

4. Nuts are your run-to snack for protein and magnesium. In addition to that they are high in oils and therefore high in calories.

5. Meats, chicken, fish and beans are your best protein and also supply you with enough Iron. This means that vegans will have to be more intentional about using iron-rich drinks like Hibiscus and Beetroot for more Iron. Female ultra-runners may choose to supplement Iron during their menstruation week if there is a history of Iron deficiency anaemia.

6. If you are lactose intolerant, you can use non-milk sources of protein however ensure a good intake of Calcium.

7. Go for a CBC, to check Hemoglobin (Hb) levels as low Hb harms your performance.

8. Yes, you may have more questions. Please consult as this article does not exhaust all aspects of exercise nutrition.

About the Writer: Nantege Regina

Founder and Lead Dietitian at Lya Dietitian App, Experiences Sports Nutrition through Runs and Hikes.

X: @RegisDietitian Email: Phone: +256784200201